Norris also went on to deny Celtic a penalty for a similar offence against Andy Webster deep into stoppage time.
"It's inconsistency from the referee," Thompson told Sky Sports News. "If one's a penalty, the other one's a penalty. Initially we don't think the Hearts one is a penalty. It's come off Joe Ledley's foot and come up to his hand. He's so close to the ball he can't get out of the way.
"If he does give the penalty, we would like to think that the Webster one just after that is also a penalty. There is an inconsistency in how the referee sees it."
Celtic's defeat has cost them the chance of securing a domestic double.