Villain could easily have Q-Q, J-J, 10-10, or a strong ace here. You said the initial raiser was loose, right? It sure looks like villain has a big hand and is trying to isolate the first raiser. He may have had aces, but I think it's +EV to reraise Villain preflop and bet the flop like you got the nuts. Looks like an isolation play to me, so I'm not so certain it was aces.