50NL - Line check?

never played villain before. about 20 hands in. seems passive. no other reads. thoughts on this hand?

PokerStars Game #13914230002: Hold'em No Limit ($0.25/$0.50) - 2007/12/17 - 01:19:35 (ET)
Table 'Patricia' 2-max Seat #1 is the button
Seat 1: daav1d ($51.60 in chips)
Seat 2: HERO ($69 in chips)
daav1d: posts small blind $0.25
HERO : posts big blind $0.50
*** POCKET CARDS ***
Dealt to HERO [Ac 7s]
daav1d: raises $1.50 to $2
HERO: calls $1.50
*** FLOP *** [3s 9s As]
HERO: checks
daav1d: bets $2.50
HERO: raises $5 to $7.50
daav1d: calls $5
*** TURN *** [3s 9s As 2h]
HERO: bets $12.50
daav1d: calls $12.50
*** RIVER *** [3s 9s As 2h Ah]
HERO: checks
daav1d: bets $29.60 and is all-in
HERO: calls $29.60