One of those weird 1 pair hands with position

[CrackerZack]

Ok here's the situation. SB has done a few semi-strange things, but nothing completely ridiculous from what I've seen. He's been flopping really good though and has built a huge stack. He's willing to limp and call raises with questionable hands, but there hasn't been a heavy action hand where you showed down crap so he's suspect, but not sure he's real bad.

PokerStars No-Limit Hold'em Tourney, Big Blind is t150 (9 handed)

MP2 (t5500)
MP3 (t5940)
CrackerZack (t5620)
Button (t4250)
SB (t10610)
BB (t1805)
UTG (t4225)
UTG+1 (t4894)
MP1 (t3435)

Preflop: CrackerZack is CO with K[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/club.gif[/img].
UTG folds, UTG+1 folds, MP1 folds, MP2 folds, MP3 folds, CrackerZack raises to t525, Button folds, SB calls t450, BB folds.

Flop: (t1200) 2[img]/images/graemlins/diamond.gif[/img], 7[img]/images/graemlins/heart.gif[/img], T[img]/images/graemlins/club.gif[/img] <font color="blue">(2 players) </font>
SB checks, CrackerZack bets t850, SB calls t850.

Turn: (t2900) A[img]/images/graemlins/spade.gif[/img] <font color="blue">(2 players) </font>
SB checks, CrackerZack bets t2150, SB calls t2150.

River: (t7200) 3[img]/images/graemlins/diamond.gif[/img] <font color="blue">(2 players) </font>
SB checks, CrackerZack bets t2095 (All-In), SB calls t2095.

Final Pot: t11390

I hate going to war in NL with one pair. Should I have checked the flop? Checked the river? Smaller bets?

Thanks in advance,
Zack