You guys are right. I called. He had A,K diamonds. I won.

The way he bet it made me think he had a big draw just like that. However, I wondered why he hadn't acted on the flop. Earlier on this trip, I moved in twice with straight and a flush draws with hands I should have released before the flop. I didn't win either huge pot. From now on I draw along slower.

I think he would have made a lot better play if he put you to a decison on the flop.

He has much better odds for his draw on the flop. That would have been the time to move it all-in, representing aces. (not knowing you have a set of course.)