AKo in 100NL

[DWarrior]

CO is 34/7/3.17 after 80 hands, hasn't done anything crazy. Around 8:30 my time (EST), he's in Europe.

Party Poker No-Limit Hold'em, $ BB (9 handed) pokerhand.org hand converter

CO ($117.40)
Button ($150.11)
SB ($129.90)
BB ($72.40)
UTG ($230.57)
UTG+1 ($58.50)
Hero ($191.55)
MP2 ($102.35)
MP3 ($135.40)

Preflop: Hero is MP1 with K[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/heart.gif[/img]. SB posts a blind of $0.50.
<font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises to $4</font>, <font color="#666666">2 folds</font>, CO calls $4, <font color="#666666">3 folds</font>.

Flop: ($9.50) K[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $9</font>, <font color="#CC3333">CO raises to $25</font>

Results in white below: <font color="#FFFFFF">
Hero folds.

Final Pot: $43.50

No showdown. CO wins $43.50.
CO shows Jd Td </font>

What's your line here?

I probably would have called a min-raise and check/called (unless he bet out of line), but this raise was too much for my liking. I couldn't figure out which hands he could have that I could beat: KJ, AQ, AJ wouldn't have raised; I'm splitting with AK; I'm behind sets, AA, KK, KQ, JT.

What do you think, was this a weak/lucky fold or a good read?