Do you actually think your opponent is going to put you on an ave high flush if you push the flop? You bet the flop, and get raised & you have the nuts. Your opponent likely thinks he has the best hand, so why make him think otherwise. Why take him out of the lead. By pushing with an ace high flush on the flop you only make your opponent re-think his hand strength. If you smooth called the raise w/ the nut flush you would probably get all his chips on the turn. Most players would not push an ace high flush here except for beginners who are so excited they can't contain themselves. If I was Villain and you cam right back over the top of me on the flop I would be thinking one of 3 things:
1)you have AA w/ the A of hearts
2)you have KK w/ the K of hearts
3)you have QQ for a set

Those hand make the most sense given the fact that you re-raised preflop if you were to push the flop. There could be an outside chance that you had AQ with the ace of hearts but most players wouldn't make this play. There's also a chance that your opponent won't even be thinking about what you have. He may be a donk. It is NL25. Granted there are some good players at this level, there are still plenty of donks.