The manager's mood was in stark contrast to his demeanour after the shock 2-1 home defeat by Aberdeen in the Scottish Cup last weekend - and he was delighted with the overall improvement as Anthony Stokes' hat-trick won the day.
"I am very happy. It was a brilliant performance almost from start to finish," the Celtic manager said. "I couldn't be happier with the performance or with the support we got today.
"I thought Nir Biton was superb today. Leigh Griffiths worked tirelessly for the team and I've yet to mention my hat-trick hero. He's a good player, Anthony. Overall this season, he has been excellent. A lot of players can be very pleased with their contribution today."
Lennon also laughed off press reports that he was set to consider his position at the club where he has won two consecutive Scottish titles.
"I'm in a very privileged position here. What I said was this season hasn't been as good as last season," he said.
"Every year it gets harder, more and more claustrophobic. It can be quite suffocating at times. It has been a tough season away from the pitch but on the field we've still got a very good team."
St Johnstone remain just one point ahead of Hibs in the race for a top-six finish and their manager Tommy Wright admitted his side had not been at their best.
"I thought Celtic were excellent and passed it really well and kept us under pressure," said Wright. "There are things that we could have done better but it is difficult coming here.
"We didn't keep the ball well. We got the ball in wide areas. Instead of taking people on we kept coming out wide. I'm not going to be too hard on my players, we've been excellent all season.
"It was just a frustrating day for Stevie May. Our season won't be judged on this, we have big games coming up. We need to pick up points and move away from Hibs."