Strange all-in (JJ flop T98)

[grasiu]

Party Poker
No Limit Holdem Ring game
Blinds: $1/$2
9 players
Converter

Stack sizes:
UTG: $126
UTG+1: $220.30
MP1: $77.29
<font color="red">Villain: $429.59
Grasiu: $254.15</font>
CO: $208.25
Button: $200
SB: $263
BB: $442.82

Pre-flop: (9 players) Grasiu is MP3 with J[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/diamond.gif[/img]
UTG folds, UTG+1 calls, MP1 folds, Villain calls, <font color="#cc0000">Grasiu raises to $6</font>, 4 folds, UTG+1 calls, Villain calls.

Flop: 8[img]/images/graemlins/spade.gif[/img] T[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/club.gif[/img] ($21, 3 players) Pot: $21.00
UTG+1 checks, Villain checks, <font color="#cc0000">Grasiu bets $9</font>, UTG+1 folds, <font color="#cc0000">Villain raises all-in $423.59</font>, Grasiu folds.
Uncalled bets: $423.59 returned to MP2.

Villain was playing quite agressivly, but rather poor, being in too many pots. He has done some other uncommon moves before, but not such strange ones. I have no deeper read on him. Was it a propper fold? I think he might have been on a nut flush draw or he had a set...