Is he bluffing?

[recallme]

Villain i regular tag, we haven`t tangled much this session.

Poker Stars
No Limit Holdem Ring game
Blinds: $10/$20
6 players
Converter

Stack sizes:
UTG: $3827.45
Hero: $2237
CO: $2023
Button: $2000
SB: $4497.10
BB: $2000

Pre-flop: (6 players) Hero is UTG+1 with Q[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/club.gif[/img]
UTG folds, <font color="#cc0000">Hero raises to $70</font>, CO folds, Button calls, 2 folds.

Flop: 6[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/spade.gif[/img] 3[img]/images/graemlins/spade.gif[/img] ($170, 2 players)
<font color="#cc0000">Hero bets $120</font>, Button calls.

Turn: 4[img]/images/graemlins/club.gif[/img] ($410, 2 players)
Hero checks, <font color="#cc0000">Button bets $340</font>, Hero calls.

River: K[img]/images/graemlins/club.gif[/img] ($1090, 2 players)
Hero checks, <font color="#cc0000">Button bets $860</font>,

The spades missed and this would be a great occasion to bluff for him, but is he bluffing twice?