50NL AQo: c-bet got called, double barrell the turn here?

[BoozeHound]

Hank, ama, others looking at the turn AF thread. Here's a hand with 58/15/3 where I checked behind the turn and got bet off the hand. Let's get a few of these up here for discussion. I would say kings look to be a huge part of this villains range, along with any suited connectors. Anyone double barrell here?

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.25/$0.50
5 players
Converter (http://www.neildewhurst.com/hand-converter)

Stack sizes:
UTG: $50.25
CO: $56.65
Hero: $50
SB: $54.70
BB: $74.25

Pre-flop: (5 players) Hero is Button with A/images/graemlins/spade.gif Q/images/graemlins/diamond.gif
2 folds, <font color="#cc0000">Hero raises to $2</font>, SB calls, BB folds.

Flop: 4/images/graemlins/spade.gif 5/images/graemlins/spade.gif K/images/graemlins/spade.gif ($4.5, 2 players)
SB checks, <font color="#cc0000">Hero bets $3</font>, SB calls.

Turn: 7/images/graemlins/heart.gif ($10.5, 2 players)
SB checks, Hero checks.

River: 9/images/graemlins/club.gif ($10.5, 2 players)
<font color="#cc0000">SB bets $6.5</font>, Hero folds.
Uncalled bets: $6.5 returned to SB.

Results:
Final pot: $10.5

[Check_The_Nuts]

that AF is really high considering how loose he is postflop. I would think he bets or check raises a spade draw on the flop. I wouldn't bet because he has a king here always, and isn't going to lay it down on the turn very often (excluding cases where his fold to flop bet is really low, but in that case I would think he donks the turn a lot to get his AF that high)....