I'm new to the forums, but not to poker and here is what I'm getting from this:

Some players will call with any pocket pair just to see the flop to see if they picked up a set. I think it's unlikely that he called with 22, but possible with 33 or 66. In which case your beat.

Now I don't like how he is just calling your bets throughout the hand. It seems to indicate that possibly he does have the set, because I believe a KK or QQ, possibly even a JJ would raise you to try to scare you away.

It's a real tough decision and I may not be the best person to say this, but probably checking in the long run would be the better decision, first if he puts out a huge bet then you are in a bad position and I frankly wouldn't know what to do, AA is hard to lay down in those situations.

If he just checks, he may have just had the lower pair and didn't think you had the rockets. Thats just my opinion.