On at least single player races, I've noticed that after a mandatory pit stop the game seems to get confused as to what your position is, until you get past about half a lap. If you have Crew Chief on you will likely hear some blue flags during this time. The game will also report your position as further back but once you get about half a lap in, it will correct itself. It might also affect the AI as well since they are supposed to react to being lapped/blue flag conditions now. I saw one AI inexplicably give up its position to another AI. It was coming down the straight while the other was exiting the pits, it pulled ahead by half a car length but then gave it back before the turn even though it had the inside position.