Top pair good kicker, weird river

[Vammakala]

PokerStars No-Limit Hold'em Tourney, Big Blind is t30 (8 handed) pokerhand.org hand converter

SB (t1895)
Hero (t1480)
UTG (t1550)
UTG+1 (t5365)
MP1 (t2925)
MP2 (t1665)
CO (t1560)
Button (t1740)

Preflop: Hero is BB with J[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">MP1 raises to t90</font>, <font color="#666666">2 folds</font>, Button calls t90, <font color="#666666">1 fold</font>, Hero calls t60.

Flop: (t285) 6[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, MP1 checks, Button checks.

Turn: (t285) T[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets t210</font>, MP1 calls t210, Button calls t210.

River: (t915) 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, <font color="#CC3333">MP1 bets t540</font>, <font color="#CC3333">Button raises to t1080</font>, Hero ???

Just got transferred to new table and haven't seen these guys before. I think the whole hand was a bit confusing. I think MP1 probably has two overcards and is bluffbetting the river but what is button raising with that he didn't raise earlier? Should I push/call (essentially the same thing) or fold?