The 23-year-old is well aware that not all Hoops fans were glad to see him sign from Wolves in January for a fee believed to be around £800,000 but he surely turned the sceptics around with an impressive performance against Caley which won him the match ball and a call-up to Gordon Strachan's Scotland squad for the friendly against Poland in Warsaw on Wednesday night.
His first goal especially pleased Lennon as in predatory style the former Hibernian forward darted to the front post to knock an Emilio Izaguirre cross past Inverness goalkeeper Dean Brill, who was also beaten by Charlie Mulgrew and substitute Kris Commons during a torrid afternoon.
Lennon bought Finland striker Teemu Pukki from Schalke and Amido Balde from Vitoria Guimaraes as replacements for Hooper last summer and neither could make the bench as Griffiths, with four goals in four games, cemented his place at the top of the pecking order.
"I am delighted for him and he could have had a lot more over the course of the game," said the Northern Irishman, whose side remain 21 points clear of Aberdeen at the top of the table.
"His first goal pleased me the most. We have been crying out for a penalty-box striker and that was a great ball and a great finish.
"He doesn't get disappointed (when he misses), he's hungry for more chances and he took his second and third goals brilliantly.
"His work-rate has always been good and his goal record is great. I think there's more to come from him in terms of his link-up play as well.
" He can play on his own. He's a very intelligent footballer and he can score individual goals.
"We saw a glimpse of what's ahead of us and I hope he thrives in the environment. It looks like he is enjoying himself."
Griffiths was "buzzing" to be given the chance to possibly win his fifth cap but admitted he thought his first Celtic hat-trick might never come.
He said: "After Anthony Stokes gave me the ball back and I ballooned it over the bar, I thought my chances had gone.
"But as soon as Kris Commons came on, he gave me a good through ball and I just managed to tuck it away."
Inverness arrived in the east end of Glasgow unbeaten in six games and looking forward to the Scottish League Cup final against Aberdeen in a fortnight's time at the same venue but they were fortunate only to lose five goals.
Manager John Hughes said: "We played 4-4-2 when we could have packed the midfield and the defence.
"The boys wanted to have a go and in hindsight you're asking yourself if that was right or wrong.
"But that's where we are, we're having quite a good season and playing with confidence. But given our defensive record it's disappointing to lose five goals - we could have prevented one or two."