[mongidig]

His sigh could mean that he has AA or AK and is angry at himslef for checking the turn and now having to call two cold. Or he may be the type who simply cannot let go of a big pair. Or he has a flush draw and has to call two cold not ending the action.

It would be strange for him to check the turn with a hand that has you beat. The pot is big, you may get two calls because of this and you probably are not going to get raised. I like the bet on the end.