QQ FTP NL$50 - Line check

[mrpotto]

Villain just sat down after buying in for $35 and I had no reads. How bad is the river call here? Was checking the flop, after re raising, horrible? Line check here please.

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.25/$0.50
6 players
Converter

Stack sizes:
UTG: $61.80
UTG+1: $50
CO: $35.30
Button: $19.25
SB: $57
hero: $53.20

Pre-flop: (6 players) hero is BB with Q[img]/images/graemlins/club.gif[/img] Q[img]/images/graemlins/diamond.gif[/img]
2 folds, <font color="#cc0000">CO raises to $1.75</font>, Button calls, SB folds, <font color="#cc0000">hero raises to $7.25</font>, CO calls, Button folds.

Flop: 8[img]/images/graemlins/club.gif[/img] 5[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/heart.gif[/img] ($16.5, 2 players)
hero checks, CO checks.

Turn: 6[img]/images/graemlins/heart.gif[/img] ($16.5, 2 players)
<font color="#cc0000">hero bets $8</font>, CO calls.

River: 5[img]/images/graemlins/diamond.gif[/img] ($32.5, 2 players)
hero checks, <font color="#cc0000">CO is all-in $20.05</font>, hero calls.

Results:
Final pot: $72.6