Live 10/20, surprising river check/raise

[PokerFink]

Bellagio 10/20, 9-Handed

Villian is basically unknown. Seems like the normal middle-age Bellagio 10/20 type. Relevant stacks are about 2300.

We did play a pot that I guess is somewhat relevant because neither one of us slowplayed. He bet the flop with a straight draw and I called with the same draw, we both hit the nuts on the turn and he led, I raised, he pushed, I called obv and chop chop.

Hero has J [img]/images/graemlins/diamond.gif[/img] 9 [img]/images/graemlins/diamond.gif[/img] in hijack.

Preflop
Hero opens to 80, BTN calls, SB calls, BB (villian) calls.

Flop (320): 9 [img]/images/graemlins/spade.gif[/img] 4 [img]/images/graemlins/heart.gif[/img] 3 [img]/images/graemlins/diamond.gif[/img]
SB checks, BB checks, Hero bets 240, BTN folds, SB folds, BB calls.

Turn (800): 3 [img]/images/graemlins/club.gif[/img]
BB checks, Hero checks quick.

River (800): 5 [img]/images/graemlins/spade.gif[/img]
BB checks, Hero bets 440, BB raises to 1440, Hero...

Woah, where did that come from? I checked the turn because I felt a river bet was better than a turn bet for getting value, and now, wtf?

Getting about 2.7:1 on the call.