Flopped flush facing river raise on 4straight board

[njdoo]

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.25/$0.50
6 players
Converter

Pre-flop: (6 players) Hero is BB with 3[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/spade.gif[/img]
<font color="#cc0000">UTG raises to $1</font>, 4 folds, Hero calls.

Flop: T[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/spade.gif[/img] ($2.25, 2 players)
Hero checks, UTG checks.

Turn: Q[img]/images/graemlins/diamond.gif[/img] ($2.25, 2 players)
<font color="#cc0000">Hero bets $2.25</font>, UTG calls.

River: 8[img]/images/graemlins/club.gif[/img] ($6.75, 2 players)
<font color="#cc0000">Hero bets $5</font>, <font color="#cc0000">UTG raises to $15</font>

Guy is 36.7/13.3 7 river aggression factor
Do you shove?