Flopped middle set- caution on turn?

[KHALI]

2/4 Hero is UTG+2 with 5d 5c

Table was pretty passive with lots of limping.

UTG limps, UTG+1 limps, Hero limps, Co raises(he is decent/tight), BB calls

Flop is As 5h 3c

BB bets, fold, hero calls, CO calls. ( plan was to reraise and trap blind in the middle but would you raise here or wait until turn?) The call here kind of puzzled me.

Turn 9s

BB bets, Hero raises, Co 3 bets, BB calls, Hero calls )is cap and check call an option here? Or cap and call a river raise?)

Co flat call on flop and 3 bet now had me worried(AA, 99?)

River 8d

BB checks, Hero checks, CO bets, BB folds, Hero calls

[mute]

Going for the flop check/raise looks good to me. Given that CO only called your hand is still well concealed on the turn and CO 3betting is not enough to convince me that I'm beat. Throw caution to the wind, cap the turn, lead the river and call a raise.

[Fat Nicky]

If it is true that CO is solid, then I like calling down instead of capping the turn. This certainly does look like some kind of slowplayed monster or 99. Could be 33 as well. I don't think a decent/tight player 3-bet the turn w/AK or AQ.