Sometimes I bet - nut flush on paired board PL100

[Hopscotch]

PokerStars Pot-Limit Omaha High, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

SB ($499.55)
BB ($63.60)
Hero ($267.45)
MP ($88.45)
CO ($37.30)
Button ($196.30)

Preflop: Hero is UTG with A[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/spade.gif[/img].
Hero calls $1, MP calls $1, <font color="#666666">1 fold</font>, <font color="#CC3333">Button raises to $5.5</font>, <font color="#666666">1 fold</font>, BB calls $4.50, Hero calls $4.50, MP calls $4.50.

Flop: ($22.50) 4[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, Hero checks, MP checks, Button checks.

Turn: ($22.50) J[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, Hero checks, MP checks, Button checks.

River: ($22.50) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, <font color="#CC3333">Hero bets $21.4</font>

Crazy to value bet this? I would think someone would have bet their full house by now.