$109 TPMK facing PSB on river

[Miklan300]

Sigh, I never really know whether to call or fold here. Am i donk for thinking he could be bluffing here?

PokerStars No-Limit Hold'em Tourney, Big Blind is t20 (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

MP3 (t3440)
Hero (t3250)
Button (t2560)
SB (t2950)
BB (t3030)
UTG (t2940)
UTG+1 (t2950)
MP1 (t3000)
MP2 (t2880)

Preflop: Hero is CO with J[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">5 folds</font>, <font color="#CC3333">Hero raises to t60</font>, Button calls t60, <font color="#666666">1 fold</font>, BB calls t40.

Flop: (t190) 4[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">Hero bets t140</font>, Button calls t140, BB folds.

Turn: (t470) 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets t340</font>, Hero calls t340.

River: (t1150) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets t1060 Hero???