Going too far with blind steal

[KaatzMeow]

FTP .25/.50 Limit 9 max, pretty tight table with 3 players postflop most often.

BB is 56.7/3.3/1.0/90 hands
Hero in CO with K [img]/images/graemlins/club.gif[/img] 9 [img]/images/graemlins/club.gif[/img]

Folded to Hero who raises, BB calls

Flop: 5 [img]/images/graemlins/heart.gif[/img] Q [img]/images/graemlins/spade.gif[/img] K [img]/images/graemlins/diamond.gif[/img]

BB checks, Hero bets, BB calls

Turn: A [img]/images/graemlins/diamond.gif[/img]

BB bets, Hero ????

I just wanted to check if this is a leak. Low AF postflop and he signals he has an A. Of course Ax is what many players play so this maybe a routine fold with a small pot. How about if all cards were a couple of demoninations lower. Still a fold?