[150NL] 88 Flopped set 550bb's Deep

[Benzooor]

Villain is Danibus, a good TAG running 23.4/12.9/1.5 over 300+ hands. I have never really tangled with him, and he doesnt get too out of line. I have called him on one bluff and shown a bluff but we have not really gotten involved.

Full Tilt No-Limit Hold'em, $1.50 BB (6 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Button ($187.95)
SB ($300)
BB ($653.50)
UTG ($1046.95)
Hero ($824.70)
CO ($206.85)

Preflop: Hero is MP with 8[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/heart.gif[/img].
<font color="#CC3333">UTG raises to $5.25</font>, Hero calls $5.25, CO calls $5.25, <font color="#666666">1 fold</font>, SB calls $4.50, <font color="#666666">1 fold</font>.

Flop: ($22.50) 4[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, <font color="#CC3333">UTG bets $18</font>, Hero calls $18, CO folds, SB folds.

Turn: ($58.50) A[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets $37.5</font>, <font color="#CC3333">Hero raises to $101</font>, <font color="#CC3333">UTG raises to $338.5</font>, Hero calls $200.

River: ($698) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets $722.70, and is all in</font>

Is this a fold?