the fact that he didnt have to put any money in preflop could mean he has any number of hands including 25, 23, 46, maybe TPGK, maybe semi-bluffing a flush draw (although if i was doing that i wouldnt have called the re-raise).... like i put in an earlier post, with AA you will either

1) win a small pot (the blinds/ante's, maybe a lil more)
OR
2) lose a big pot (to a raggedy 2 pair or straight, where you go all in and he has close to the nuts)

i would play a little slow, but i would have at least doubled the blinds preflop because you dont want him calling with a 24, if he catches, your screwed because your not expecting it.

-Chris