The Hoops returned from the winter break which included a training camp in Spain to hit the ground running with two convincing wins at Parkhead.
A 4-1 thrashing of Hearts was followed by a 4-0 thumping of Dundee United, results and performances which cemented their place at the top of the Scottish Premier League and buoyed the Celtic boss ahead of the trip to the national stadium where they have the chance to reach the first cup final of the season.
"I am delighted, they have played great," said Lennon.
"Playing at home this season, at times, was a bit of a bugbear but they seem to have found their mojo at home and the last two performances have been superb.
"One of the criticisms I had of the team, particularly in domestic games, was that back to front we were excellent in our build-up (but couldn't score).
"We had about 70 per cent possession against Hibs and couldn't score but now we have found our goalscoring touch in the last two games and that is really pleasing.
"I have no idea (why), maybe they just needed a break.
"But I looked at the schedule coming up and it is really heavy, there is no respite for the players."
The in-form Parkhead men are overwhelming favourites to beat a struggling St Mirren team who have not won a point nor even scored a goal against Celtic in their last eight meetings.
Lennon, though, insists the Scottish Football League-sanctioned match ball, which will be used at Hampden on Sunday, could have an effect on the outcome of the game.
"It might seem insignificant to most people but it is very important that the players adapt to the ball as quickly as possible," said the former Celtic skipper.
"It is lighter and has more of a laminate coating than the balls we use in the SPL.
"They travel differently and move in the air a bit differently so for the goalkeepers and outfield players it is very important that they adapt."