NL50: is it possible that the villain is bluffing?

[hielo_uno]

i've been stealing alot, and my image is kind of crappy
villain is 17/4/3, i think i over played my pair, but he might be playing back with a draw and missed,no?

Full Tilt Poker - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 9 Players - (LegoPoker HH Converter)

SB: $59.95
BB: $62.60
UTG: $54.20
UTG+1: $25.95
MP1: $58.15
MP2: $8.75
MP3: $54.25
Hero (CO): $58.90
BTN: $56.35

Preflop: Hero is dealt 7[img]/images/graemlins/club.gif[/img] 8[img]/images/graemlins/club.gif[/img] (9 Players)
5 folds, <font color="red">Hero raises to $2.00</font>, BTN folds, SB calls $1.75, BB folds

Flop: ($4.50) 5[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $3.00</font>, <font color="red">SB raises to $8.50</font>, Hero calls $5.50

Turn: ($21.50) T[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">SB bets $15.00</font>, Hero calls $15.00

River: ($51.50) Q[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">SB bets all-in for $34.45</font>