NL50 - Full House on Board - Facing Shove

[MonkeyButler]

PokerStars No-Limit Hold'em, $0.50 BB (7 handed) Hand History converter Courtesy of PokerZion.com

CO ($50)
Button ($90.80)
Hero ($72.10)
BB ($48.80)
UTG ($44.75)
MP1 ($6.05)
MP2 ($59.25)

Preflop: Hero is SB with 4[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/spade.gif[/img].
<font color="#666666">5 folds</font>, <font color="#CC3333">Hero raises to $2</font>, BB calls $1.50.

Flop: ($4) 3[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $2.5</font>, BB calls $2.50.

Turn: ($9) Q[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $3.5</font>, <font color="#CC3333">BB raises to $11</font>, Hero calls $7.50.

River: ($31) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">BB bets $33.3 (All-In)</font>.

This is an interesting hand that came up and I couldn't make a decision on. Reads that I had was that he bet for value, he showed down solid hands, and I hadn't seem him showdown a bluff.

He shoves here why? Is he holding a pair higher than my 4s and is trying to think that i'm going to play the board, and therefore trying to donk me into calling? Or is HE playing the board and just hoping for a fold from me rather than a split pot?

All feedback appreciated... also, if there's a problem with my line at any point, please feel free to rip me a new one.