CO is pretty very tight and solid play , He hasn't play anything much (about 2 hands from 20 hands)

PokerStars Game #32746252791: Hold'em No Limit ($0.05/$0.10 USD) - 2009/09/12 6:37:47 ET
Table 'Glauke III' 9-max Seat #9 is the button
Seat 1: Me ($22.35 in chips)
Seat 2: BB ($1.85 in chips)
Seat 3: UTG ($1.50 in chips)
Seat 4: UTG+1 ($6.35 in chips)
Seat 5: MP1 ($7.90 in chips)
Seat 6: MP2 ($1.80 in chips)
Seat 7: MP3 ($2 in chips)
Seat 8: CO ($11.35 in chips)
Seat 9: Button ($9.85 in chips)
Me: posts small blind $0.05
BB: posts big blind $0.10
*** HOLE CARDS ***
Dealt to Me [Ks Kh]
UTG: folds
UTG+1: calls $0.10
MP1: folds
MP2: folds
MP3: folds
CO: raises $0.30 to $0.40
Button: folds
Me: calls $0.35
BB: folds
UTG+1: calls $0.30
*** FLOP *** [4h Tc 5h]
Me: checks
UTG+1: bets $0.20
CO: raises $0.80 to $1
Me: calls $1
UTG+1: calls $0.80
*** TURN *** [4h Tc 5h] [5d]
Me: checks
UTG+1: checks
CO: bets $2.50
Me: calls $2.50
UTG+1: calls $2.50
*** RIVER *** [4h Tc 5h 5d] [6d]
Me: checks
UTG+1: checks
CO: bets $7.45 and is all-in
Me: folds
UTG+1: folds
Uncalled bet ($7.45) returned to CO
CO collected $11.25 from pot

I think he had AA or hitting a set with TT