Tough spot 25/50

[MezmerizePLZ]

POKERSTARS GAME #8288001309: HOLD'EM NO LIMIT ($25/$50) - 2007/02/05 - 02:10:53 (ET)
Table 'Marmulla II' 9-max Seat #4 is the button
Seat 1: Grimstarr ($11542 in chips)
Seat 3: MezmerizePLZ ($5871 in chips)
Seat 4: MrSweets28 ($5825 in chips)
Seat 5: socutiesf ($1001 in chips)
Seat 6: eddy81 ($5522 in chips)
Seat 9: play2kill ($5075 in chips)
socutiesf: posts small blind $25
eddy81: posts big blind $50
*** HOLE CARDS ***
Dealt to MezmerizePLZ [Ad Td]
play2kill: folds
Grimstarr: raises $100 to $150
MezmerizePLZ: calls $150
MrSweets28: folds
socutiesf: folds
eddy81: calls $100
*** FLOP *** [2d 9h Ac]
eddy81: checks
Grimstarr: bets $350
MezmerizePLZ: calls $350
eddy81: calls $350
*** TURN *** [2d 9h Ac] [Tc]
eddy81: checks
Grimstarr: checks
MezmerizePLZ: bets $850
eddy81: raises $4172 to $5022 and is all-in
Grimstarr: folds
MezmerizePLZ: ?????

I don't know this player well at all - he doesn't seem like a nit, but he doesn't seem like a retard, with his overcall on the flop he defniately has a piece of the board, it seems the only hands he can have here are 22/99/AT also, (maybe A9????) i'd think he would raise that on the flop along with A2. I know my turn bet is small and i should have made it larger, thought the pot was slightly smaller than it was.. thoughts?