[RobNottsUk]

Because the CO's likely feeling you out, hoping you cbet with a 'busted' A2xx. I think 3-betting the flop is good, but then slow down if the turn's a 4 especially, though 5 might be bad to.

The problem is that CO could have something like 532dKd, where the made Lo + flush draw, becomes a nice free-roll against your hand. Similar Hi hand wrap possibilties, could have tempted the CO to make a free card play. It could also be 2nd set Q's with a better Lo draw than yours.

Argues to me, to get the money in whilst you can, and bet/call turn unless you can narrow their raising hand down, in which case check/call on a scare card.

Near this level, I have had 1 or 2 opponents make good free card plays on the flop, most often it's an opponent trying to isolate me and hoping I've A2xx and cbet.

Another hand that happened, I flopped a full house + good Lo draw, and faced unexpected aggressive raises. The Fishy opponent was on a wheel str8 draw + Lo draw (didn't care about A's full possibility), and caught runner-runner cards to scoop me both ways!