Not raising with KK on good flop

[Mjonasson]

PT-stats(about 65-80hands for all of them):
CO: 29% VP$IP, 14% PFR, 1,73 Total agg
Button: 80%VP$IP, 9%PFR, 0,89 Total agg
BB: 36.14% VP$IP, 6%PFR, 1.21 Total agg

Party Poker 2/4 Hold'em (10 handed)

Preflop: Hero is MP1 with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#666666">3 folds</font>, <font color="#CC3333">Hero raises</font>, <font color="#666666">2 folds</font>, CO calls, Button calls, <font color="#666666">1 fold</font>, <font color="#CC3333">BB 3-bets</font>, <font color="#CC3333">Hero caps</font>, CO calls, Button calls, BB calls.
<font color="blue">Lots of action, lots of fun! [img]/images/graemlins/smile.gif[/img]</font>

Flop: (16.50 SB) 8[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">BB bets</font>, Hero calls, CO calls, Button calls.
<font color="blue">Hmmm, BBs bet doesn't really say anything. If I'm rasing CO will get 2 to 19 to call and button 2 to 21(if CO calls). That and the fact that they are loose makes me just call here, intending to raise the turn.</font>

Turn: (10.25 BB) A[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, Hero checks, CO checks, Button checks.
<font color="blue">Auch, Here comes the ace, probably at least someone got an ace here, so I plan to check/call here. Is this a bit to weak?</font>

River: (10.25 BB) K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, <font color="#CC3333">Hero bets</font>, CO calls, Button folds, BB folds.
<font color="blue"> Ahhh, this we like. Standard bet right? Check-raise feels a bit dumb, people might just check along. </font>
Final Pot: 12.25 BB

So how about this play? To weak and passive?