BB COULD possibly be holding KK? Your flop bet was weak, maybe he doesn't believe you have an Ace. Although if that's the case he SHOULD have raised or folded. But on the turn he could have picked up a flush draw, with the K of hearts perhaps?

UTG we don't have any stats on? If he's tight he'll probably have a pocket pair, now again he should be raising the flop though.. it all depends on how aggressive and loose your villians are to be able to put them on hands successfully.