The Dons centre-half brought down Gary Hooper inside the opening 20 minutes of yesterday's Scottish Cup semi-final at Hampden Park, which Celtic eventually won 4-0, and Lennon admits that perhaps his side were a bit lucky to playing with an extra man for most of the game.
"Psychologically for Aberdeen it was damaging," said Lennon.
"But I do think it was a penalty and in the interpretation of the laws of the game, the referee probably had no choice but to send him off.
"I think it is one rule that could be doing with being looked at.
"If someone makes a genuine attempt to get the ball and is beaten, then maybe a penalty and a yellow card is punishment enough.
"There are cases where people are going through and are deliberately brought down and that is a different scenario altogether.
"But if someone has made a genuine attempt and is beaten by a bit of pace, I think that needs looking at."