Paying off the flush two handed

[shadow29]

Down to 2 in a live sng. Opp has ~2k to my 8k. I get the K3o in the BB, button calls, I raise 600 more (blinds at 100-200) and he calls. Flop comes Kxx of diamonds (I have no diamonds). I bet 1k, he pushes, I call. I shows J3 diamonds for the flush. He doubles up, but I eventually get all my money in (still have him outchipped) with an Ace + ace on flop to his straight draw which doesn't hit.

Just curious about paying off on flush boards and similar hands...