AA hand id never think to play like this...

[PokerCad]

If MP is as you say decent, and he probbly knows u are good, is it not possible that he played this hand to do just what he did? in that it made you take a second look at how he was playing, adding a little deception perhaps? and in hindsight not knowing you had a set he ended up saving a few bets. This is the only explanation I can come up with in why he played his hand this way.