Fire 2nd barrel on this semi-scare card?

[LOwrestling2001]

villain is 60/2/1.5 over 50 hands. calling station extraordinaire. also, is my river play standard?
PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

MP ($41.55)
CO ($23.25)
Button ($25)
SB ($24.75)
BB ($26.25)
Hero ($26.10)

Preflop: Hero is UTG with A[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">Hero raises to $1</font>, MP calls $1, <font color="#666666">4 folds</font>.

Flop: ($2.35) 6[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $2</font>, MP calls $2.

Turn: ($6.35) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $4</font>, MP calls $4.

River: ($14.35) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">MP bets $5</font>, Hero calls $5.

Final Pot: $24.35

[VPIP100]

If he is a calling station, why bet?

[bohus04]

I think this is good. He might be calling with FD and/or pair and check calling river can induce a bluff from him.(He is not that passive with 1,5AF). If he was more passive than bet river is better i think...