Poor river raise?

[RcrdBoy]

Third hand at this table so not many reads. UTG+2 is potential LAG (raised first two hands after I sat down, second was 85s).

Party Poker 1/2 Hold'em (10 handed) converter

Preflop: Hero is Button with K[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/club.gif[/img].
UTG folds, UTG+1 calls, UTG+2 calls, MP1 folds, MP2 calls, MP3 calls, CO calls, Hero calls, SB completes, BB checks.

Flop: (8 SB) 8[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/spade.gif[/img] <font color="blue">(8 players)</font>
SB checks, BB checks, UTG+1 checks, UTG+2 folds, MP2 checks, MP3 checks, CO checks, <font color="CC3333">Hero bets</font>, SB calls, BB calls, UTG+1 calls, MP2 folds, MP3 calls, CO calls.

Turn: (7 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="blue">(6 players)</font>
SB checks, BB checks, UTG+1 checks, MP3 checks, CO checks, <font color="CC3333">Hero bets</font>, SB calls, BB folds, UTG+1 calls, MP3 folds, CO calls.

River: (11 BB) A[img]/images/graemlins/club.gif[/img] <font color="blue">(4 players)</font>
<font color="CC3333">SB bets</font>, UTG+1 folds, CO folds, <font color="CC3333">Hero raises</font>, <font color="CC3333">SB 3-bets</font>, Hero calls.

I thought SB might think he beat my TP. Should I have folded to the 3bet?

In retrospect, is SB really going to call the whole way with only an A? Probably more likely he rivered the better two pair.

Thoughts?
Final Pot: 17 BB