AM I A Donkey?

[HandHack1]

Full Tilt Poker - No Limit Hold'em Cash Game - $0.05/$0.10 Blinds - 6 Players - (LegoPoker HH Converter)

SB: $8.75
BB: $3.70
UTG: $8.40
MP: $8.30
<font color="black">Hero (CO): $10.25</font>
BTN: $1.50

<font color="black">Reads: </font><font color="blue">Didn't put on AK being no big post flop raise</font>

<font color="black">Preflop:</font> Hero is dealt K[img]/images/graemlins/club.gif[/img] 4[img]/images/graemlins/club.gif[/img] (6 Players)
2 folds, Hero calls $0.10, BTN folds, <font color="red">SB raises to $0.40</font>, BB folds, Hero calls $0.30

<font color="black">Flop:</font> ($0.90) K[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/spade.gif[/img] 3[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">SB bets $0.30</font>, <font color="red">Hero raises to $1.30</font>, SB calls $1.00

<font color="black">Turn:</font> ($3.50) 2[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $3.00</font>, SB calls $3.00

<font color="black">River:</font> ($9.50) 4[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">SB bets all-in for $4.05</font>, Hero calls $4.05

Pot Size: $17.60 ($1.75 Rake)

SB had A[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/spade.gif[/img] ([Ah Ks] a pair of Kings) and LOST (-$8.75)
Hero had K[img]/images/graemlins/club.gif[/img] 4[img]/images/graemlins/club.gif[/img] (two pair, Kings and Fours) and WON ( $7.10)

I woulda folded if not for the 4 on river.