$4k Guaranteed: Weird limp behind, then reraise. Wtf is this?

[blankoblanco]

About 30 hands in, this is villain's first reraise and he hasn't limped much or played many pots. My image is TAG. I haven't played a hand since ~6 hands ago when AJ > my AKs AIPF.

What do you make of button's limp behind and then re-raise. Does he ever do this with a legitimate hand? What's your range for getting it in the middle here?

Full Tilt Poker
Pot Limit Holdem Tournament
Blinds: T25/T50
9 players
Converter

Stack sizes:
UTG: T3643
UTG+1: T2780
MP1: T2270
MP2: T2660
MP3: T3020
CO: T4239
Button: T4348
SB: T2210
Hero: T1830

Pre-flop: (9 players) Hero is BB with TWO CARDS
5 folds, CO calls, Button calls, SB calls, <font color="red">Hero raises to T250</font>, CO folds, <font color="red">Button raises to T900</font>, SB folds, Hero... </font>

Range?