Fold bottom set here?.....

[Python49]

My read on villain in this hand was that he was very good, I considered him the best player at the table. He was very tight/agg and had shown down good hands each time. I had 200 hands on him and he was 21/8....

Does anyone like this fold? If you don't fold, please tell me what you are putting him on to be reraising here. I didn't think there was anyway he limped with k/3 or k/2 and if he did he's not going to reraise it here I didn't think. Also he wouldnt be dumb enough to reraise KQ or KJ here and would def raise AK pf I thought. What do you guys think?

Party Poker No-Limit Hold'em, $ BB (6 max, 5 handed) converter

BB ($89.09)
UTG ($146.77)
MP ($270)
Hero ($109.80)
SB ($33.45)

Preflop: Hero is Button with 2[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/heart.gif[/img]. SB posts a blind of $0.50.
UTG calls $1, MP calls $1, Hero calls $1, SB (poster) completes, BB checks.

Flop: ($5) 2[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(5 players)</font>
SB checks, BB checks, UTG checks, <font color="#CC3333">MP bets $5</font>, <font color="#CC3333">Hero raises to $15</font>, SB folds, BB calls $15, UTG folds, <font color="#CC3333">MP raises to $50</font>, Hero folds, BB folds.

Final Pot: $85

Results in white below: <font color="#FFFFFF">
No showdown. MP wins $85. </font>