[NegranuFan]

what is your position?
What is "he bet small on the flop"?
What is your stack size?
His stack size?
Do you have any read on him?
Does he on you?
Also, when you raise big like that, I'd say from his/her perspective that he put you on a big hand, but likely not a big pair. With a big raise you are saying that you want 1 caller, but not THAT badly. He is 100% certain that his 2 cards are live. Depending on his read on you he might figure that a low flop that hits him huge, like 2 pair or trips, you will be hard pressed to put him on either a 7 or 3 so he essentially has the opportunity to take you whole stack, if he thinks he can outplay you after the flop.

And then again he might have sneezed and called accidentally...

Although this isn't your question, I much prefer a substantial, maybe pot sized raise on the flop because it disguses (and protects) your hand. Your raise tells him you are not afraid of the Ace (so no KK, QQ), so he can only really call with a flush draw. If he has some strange 2 pair or trips I'd expect him to reraise all in to protect it. With the pot so big already, it is unlikely that this reraise could/would be a bluff, and he would want to get the money in while he is sure he is ahead. Granted everyone sees teh all-in semi bluff on big draws, but to do so would be a mistake because he has to figure you will call more than 90% of the time, thus making it not profitable.

Any comments are welcome.