The challenge had gone stale, Scottish football was in decline, and the scene was a poor imitation of the heady days of Martin O'Neill's time at Parkhead, when Lennon led a lavish Celtic team in front of booming crowds in Glasgow's east end.
"Time to get out," on more than one occasion was Lennon's refrain to those close to him. The day of decision loomed ever large. It would have been a miracle to me had Lennon lasted five years as Celtic manager - it just would not have fitted with his mindset.
No matter what success he had, managing Celtic became a thankless task in a depressed market.
For some of us, it was impossible to relay this Lennon sentiment, either in print or on air, without receiving a savaging from clumps of Celtic fans. About five months ago I got barraged one evening on BBC Radio Scotland for thinking aloud that Lennon may think it was time to leave Celtic.
"Rubbish, you don't know what you're talking about," a caller told me. Another impassioned Celtic fan said I was havering, claiming that Lennon loved Celtic (which he does) and that he always spoke of how much he loved his job. How were we to conduct this debate properly without betraying the private Lennon? It was simply impossible.
Last Saturday Lennon confirmed to another intimate that he was leaving Celtic. This time, it really did seem that the curtain was coming down. How many months can pass, for anyone so unsettled, before it starts to affect their performance?
All that said, one of Neil Lennon's real testaments was the devotion and ardour which he brought to his job. Some people used to think of Lennon as a feckless, even an undisciplined character, but as Celtic manager he put paid to most of these accusations.
Domestically, he brought a passion and attention to detail to Celtic's every challenge against a St Mirren, a St Johnstone, a Ross County. In the Champions League - and it was a struggle sometimes just to get to that playground during a sweaty August - Lennon showed keen thought and planning which proved he was totally immersed in the ways of modern football.
During his tenure, his Celtic team played very well for 80 minutes in San Siro before a dire final 10-minute collapse against AC Milan. In Camp Nou, Lennon's Celtic also cleverly thwarted Barcelona, before succumbing at the death.
In Glasgow, famously, Barca were crushed. In all of this and more Lennon strode into the lions' den with courage and conviction, a measure of his worth to Celtic.
The problem he had was that the thunder never really did return to Celtic Park, as he had expressly wished. Champions League nights, everyone knows, are immense at Celtic, but the week-in, week-out stuff which Lennon faced became increasingly drab.
It may simply be the truth for every Celtic manager that a three or four-year span is about the limit of the job's duration. Beyond that, as Lennon found, the stimulus is harder to find.
Lennon is 42 years old. He had a decision to make: to blindly tie himself to Celtic for life (or until he got sacked) or leave and place himself on the market for a different challenge, either in England or abroad.
He has courageously gone for the latter, without a new job lined up, and when there is already a number of proven managers - David Moyes, Owen Coyle, Alex McLeish and others - unemployed.
It is easy to say it now that Lennon needed change, that he has done the right thing. But will he get a decent gig? It is interesting how, in recent days, those who previously foresaw a career for Lennon somewhere in the flabby midriff of the Barclays Premier League, are now talking about "an ambitious Championship club" as his next starting point.
Ten months ago Lennon was being linked with Everton. Now a club such as Brighton might be his next port of call. Expectations are being scaled back as the thought dawns that Lennon may face an uncertain future.
He will be sorely missed in Scotland. Few football figures over the past 30 years have triggered such debate, such controversy and such national navel-gazing as Lennon.
Some of the bigotry he has faced has been an abomination. Among certain Rangers fans Lennon has become a hate-figure, in part rooted in the memory of the Celtic team he played for, which often enough did their own team in.
One of his enduring contradictions will remain the contrast in his public and private image. In these pages yesterday, Hugh MacDonald wrote perceptively: "Lennon was articulate, precise and enlightening in interviews."
To the public Lennon is viewed as belligerent and aggressive and even nasty. Yet the Scottish football writers, almost as one, will tell you of this intelligent, affable guy who more often than not engaged them in many interesting conversations. Lennon's public and private images make for a startling contrast.
My own belief is that his alleged anxiety over the budget at Celtic for the coming season - and this being a reason for his departure - is exaggerated.
Lennon has known from day one that Celtic's finances are limited, and that the main financial players at the club, such as Dermot Desmond, simply will not pour money into Scottish football's black hole. He has absolutely no illusions about that.
Instead, Lennon wanted out. He needed change. He desired a new environment in which to test himself. His next club, wherever it is, might be quite a climbdown.
He bows out of Celtic and Scotland with some smoke and debris in his wake. It has been an amazing experience.