NL25 - Ok river fold?

[guitarizt]

I've been trying out checking the flop when I hit top pair because people never ever believe me when I check the flop. It's not going so good today though, I got hit by two backdoor flushes in 18 hands, I was able to keep the pot small but it still sucks. Here's another hand where it backfired.

PokerStars No-Limit Hold'em, $0.25 BB (5 handed) pokerhand.org hand converter

Hero ($29.10)
Button ($27.30)
SB ($28.65)
BB ($25)
UTG ($17.30)

Preflop: Hero is MP with 8[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $1</font>, <font color="#666666">1 fold</font>, SB calls $0.90, <font color="#666666">1 fold</font>.

Flop: ($2.25) 7[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, Hero checks.

Turn: ($2.25) 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $1</font>, <font color="#CC3333">Hero raises to $3</font>, SB calls $2.

River: ($8.25) 7[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets $3</font>, <font color="#CC3333">SB raises to $9</font>, Hero folds.

Final Pot: $20.25