$55: Mystified. Do donks still do this in the 55's?

[llabb]

NL Texas Hold'em $50 Buy-in + $5
Level:2 Blinds(15/30)
Seat 4 is the button
Total number of players : 7
Seat 1: urgggh ( $840 )
Seat 2: virgin99 ( $2165 )
Seat 3: mikepal1970 ( $2140 )
Seat 4: Hero ( $885 )
Seat 5: BigFold111 ( $1025 )
Seat 6: centgas20 ( $905 )
Seat 10: oasisofaces ( $2040 )
Level:2
Blinds(15/30)
** Dealing down cards **
Dealt to Hero [ Kc Ad ]
oasisofaces folds.
urgggh folds.
virgin99 folds.
mikepal1970 folds.
Hero raises [90].
BigFold111 is all-In [1010]
centgas20 folds.

Hero??

Folded around to me on the button, standard raise, SB goes all-in on level 2?!
First thought: total donk.
Second thought: He assumes I'm stealing, how bad is his range of hands to do this with?
Third thought: Uh-oh, could this possibly be a Lorinda overbet with Aces or Kings?

Thoughts on the villain's hand and my move?