getting 5:1 on river with a pair of 5s

[holdem2000]

Villain is 51/7 after 41 hands, no other reads besides more stats, which don't mean a whole lot with this sample. I don't recall, but there's a good chance I've raised a lot of his limps given his stats, so he's probably picked up on how often I steal.

Comments on all streets appreciated

Poker Stars - No Limit Hold'em Cash Game - $1/$2 Blinds - 9 Players - (LegoPoker Hand History Converter)

SB: $182.50
BB: $113.75
UTG: $121.20
UTG+1: $209.55
MP1: $390.40
MP2: $200.00
MP3: $322.95
Hero (CO): $206.00
BTN: $550.30

Preflop: Hero is dealt 5[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/heart.gif[/img] (9 Players)
2 folds, MP1 calls $2.00, 2 folds, Hero raises to $10.00, 3 folds, MP1 calls $8.00

Flop: ($23) 2[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/spade.gif[/img] 5[img]/images/graemlins/spade.gif[/img] (2 Players)
MP1 checks, Hero bets $17.00, MP1 calls $17.00

Turn: ($57) Q[img]/images/graemlins/heart.gif[/img] (2 Players)
MP1 bets $24.00, Hero raises to $72.00, MP1 calls $48.00

River: ($201) K[img]/images/graemlins/diamond.gif[/img] (2 Players)
MP1 bets $52.00, Hero ??? calls $52.00

Pot Size: $305.00 ($3 Rake