Lennon's decision to rest key players looked set to backfire as Saints led 1-0 at the break, but the introduction of Kris Commons and Scott Brown inspired a turnaround as they led 3-1 with six minutes to play.
A win would have left the champions on 98 points with a final-day home game against Dundee Untied to come, but two late goals salvaged a draw for Saints.
Asked is he was disappointed Lennon said: "Not really. You set yourself little targets and it would have been a nice milestone.
"We should have done because we were 3-1 up with 10 minutes to go, but we have scored 99 goals, we are one short for 100 and that would be nice to finish the season off with that.
"I am really looking forward to Sunday. The lads haven't had the opportunity to celebrate the title win so to get the trophy at home will be a special day and I want them to finish the season on a high.
"It was a game of two halves tonight. We were poor in the first half but very good in the second."
Referring to his side's ragged first-half display he said: "It was unacceptable. We were miles off the level we've been at. And I'm not just talking about the players that came in either. Some of the players who were playing on a regular basis weren't at it.
"I wasn't happy with our defending for the final two goals either. I thought we were lazy. There was a fluency about us in the second half which missing in the first half."
Saints have a Scottish Cup final to come, but it was a rare off-night for top scorer Stevie May, who missed a first-half penalty and was taken off at the break after a strong challenge from Efe Ambrose.
Boss Tommy Wright said: "Stevie's fine. The plan was to give him only 60 minutes anyway. He took a nasty one, stud marks on his shin, but there's no problem with it at all. It was just precaution he came off.
"I was delighted with the performance. We deserved a point. Other than the penalty miss we had other opportunities to be more than just one ahead."