Pre-flop: I prefer a 3b in this spot as I want to play hands like AJ with the initiative and in position. If he 4b then it is an easy fold and I doubt villain would 4b light here anyway.

As played:

I think it is interesting how villain's sizing changes on the turn and river. If you look at the flop bet, it is a standard type c-bet sizing with what we know now is a middle pair repping an ace. When you call he is most likely done with the hand unless he improves.

The turn is not a good card for villain to barrel as it usually changes very little yet he opts to go for 60% pot sizing. I really doubt whether most villains will fire a 2nd bullet of this sizing with a hand that you can beat. A lot of players will check/call or continue with the smaller bet line with hands you can beat. His sizing looks really strong to me.

The river changed nothing and he still continues with very strong sizing into you. I think at the very least now you have to be really concerned that AQ/AK is there.

I cannot say that I would find a fold in play here as I have called down enough times in these spots myself but I really feel this escalation in sizing might be a very good sizing tell in this spot and as played once we get to the river there is not much that we beat that takes a line this strong.