I think you did the right thing in betting. If he's a smarter player, he won't call you with a flush draw, so if he calls that pot bet, you're probably beat, or facing AK. Would he call a pot bet with 6's? The probability of him having 6's is low, and any other pot-bet-calling hand probably has you beat if there are 2 overcards on the board (the turn card would have to be taken into account).