In fairness, it was not exactly critical to the outcome of the Warriors' 54-0 hammering of Parma's finest that the 24-year-old centre came up short, in the most literal sense. However, at least he had the decency to hold his hand up and admit to the error when quizzed about it a few days later. "I was maybe slightly fortunate to get it," Dunbar admitted sheepishly. "But you learn from your mistakes."
Given another opportunity, as he surely will be, in the RaboDirect PRO12 semi-final match with Munster at Scotstoun tomorrow night, Dunbar might be a little more careful with his finishing. He is not exactly a try machine - that try against Zebre was his first of the current PRO12 campaign - but there is an all-round tidiness to his play that marks him out as the kind of fellow who does not have to splatter his name all over a scoresheet to justify his place on the pitch.
And maybe just as well, too, for the competition for places in the Warriors' starting XV is ferocious. Coach Gregor Townsend is spoiled for choice as far as candidates for the outside-centre berth is concerned, for as well as the obvious rival for the No.13 shirt, Mark Bennett, Townsend could just as easily ask Sean Lamont, Stuart Hogg or Richie Vernon - internationalists all - to do a shift in the position.
Having started just a handful of PRO12 games this season, Dunbar is probably a little fortunate to have been included in the league's so-called dream team, but a better measure of his worth is offered by the fact that he has become a virtual fixture in the Scotland Test side over the same period, collecting eight caps and scoring three tries since he made his debut in last summer's match with Samoa in Durban.
A couple of lengthy injury breaks restricted his appearances for Glasgow, but it is probably true to say that it is a stiffer challenge for him to get into the Warriors starting XV at the moment than it is to keep his place in the Scotland side.
"There is a lot of competition for places," said Dunbar. "But everyone is really professional about it, pushing each other hard. All we can do is train well and make it hard for Gregor picking the team. Everyone is really working hard and there is a great team spirit."
Just as well, for discontent in the ranks would do nothing to help Glasgow's cause when, on the occasion of their inaugural home play-off in the PRO12, they are in the unaccustomed position of being favourites to progress to the final. It is a prize that has eluded them on their three previous appearances at this stage of the Celtic/Italian competition.
"That's the kind of culture Glasgow is renowned for," said Dunbar of the spirit of the squad. "Even the boys who are not involved or injured will do anything possible. Finn [Russell] and Mike Cusack were injured for a while, but they were doing a lot of analysis on teams, just helping out the coaches."
Dunbar is one of six individuals in the running for the award of Warriors' player of the season, the others being Jonny Gray, Josh Strauss, Rob Harley, Tommy Seymour and Leone Nakarawa. The four/two split between forwards and backs says something of the kind of rugby Glasgow have been obliged to play this season, but there is no question that the backs have found their feet and their scoring touches, with a flurry of tries in the unprecedented eight-game winning streak with which they closed out their regular PRO12 season.
However, even as they have racked up the try-bonus points that were so elusive earlier in the season, Dunbar is content to spread the credit for Glasgow's form on the finishing straight. "It's not just the backs, it's the whole team," he said firmly. "I think the forwards really put a marker down [against Zebre] and gave us good, quick ball to play off. But some of the backs we have here are world class so if we get the opportunity and get quick ball we can tear any team apart.
"The way we attacked Zebre was encouraging from the whole team point of view, certainly in the first half. Some of the running lines and support we had were outstanding. There are a lot of positives to take into this weekend and Munster, but we still know we have to start again and put in another performance."
Townsend is obliged to name his side before 12 noon today. Much of the speculation around possible permutations has centred on whether Al Kellock, inspirational as a captain but under pressure in the second row, will keep his place, whether Peter Murchie will pip Stuart Hogg for the full-back berth and which fly-half will be chosen.
Glasgow have confirmed that prop Ed Kalman, fly-half Scott Wight and hooker Finlay Gillies will be released at the end of this season. Meanwhile, Edinburgh have confirmed the signing of 21-year-old Gala prop Rory Sutherland.