value bet this after he slows down?

[jar]

Party Poker 0.50/1 Hold'em (9 handed)

Preflop: Hero is Button with Q[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/club.gif[/img].
UTG calls, UTG+1 calls, <font color="666666">1 fold</font>, MP2 calls, <font color="666666">1 fold</font>, CO calls, Hero calls, SB completes, BB checks.

Flop: (7 SB) A[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/heart.gif[/img] <font color="blue">(7 players)</font>
SB checks, BB checks, UTG checks, UTG+1 checks, MP2 checks, <font color="CC3333">CO bets</font>, <font color="CC3333">Hero raises</font>, SB calls, BB folds, UTG folds, UTG+1 folds, MP2 folds, CO calls.

Is this a good raise? I felt like there was some chance a weak ace might fold, I could get an idea if someone has an ace while the bets are cheap, and there's a decent chance I have the best hand. Are these reasons sufficient? What should I do if I get 3bet by the bettor? by someone else?

Turn: (6.50 BB) 7[img]/images/graemlins/club.gif[/img] <font color="blue">(3 players)</font>
SB checks, CO checks, Hero checks.

Did I wuss out? Or is the fear of a slow played ace legit?

River: (6.50 BB) 4[img]/images/graemlins/club.gif[/img] <font color="blue">(3 players)</font>
SB checks, CO checks, Hero checks.

I feel like I should've value bet here, but I just took the free showdown.

Final Pot: 6.50 BB
<font color="green">Main Pot: 6.50 BB, between SB, CO and Hero.</font>