Of course, but that's not how player brains work - nothing aggravates them more than inconsistency and the majority of players you encounter on a Sunday morning will now believe that a yellow is mandatory for a PK at corners.
I've just been listening to a podcast discussing this and they make a very good point - the only reason the liverpool attacker wasn't being fouled after the ball was kicked is because he was already on the floor. Why do we referees do this at corners: try to stop play before it begins to warn players that they're about to foul? We don't do this elsewhere on the pitch?