A bunch of variables to account for when making this call. It depends what stage of the tournement this is at. For example, if this is before the first break, solid players (you say he hadnt done anything out of line) generally wont jepordize their entire stack without figuring they are the best and since you raised UTG and bet the flop and turn with the Ace up, he could safely put you on ACE/FACE and if he picks up a better hand then that, then he knows you will call an overbet. For example, 44(even as bad as A8s) is a callable hand out of the BB for somepeople. Therefore, when he comes over the top on the turn, there isnt alot can beat in my mind. However, if this is further into the tournement, he may call you with any ace and push when one flops. Another variable to account for in addition to the stage of the tourney is the size of their stack. if you have them covered- would it be worth it for them to bluff at a pot when you have showed strength from UTG with an Ace up? Unlikely. This post is starting to get too long so all i have to say is, avoid getting tangled up in marginal situations in the first stage of the tourney, and a players stack is a good indication of how they will play certain cards/flops.