Cold caller pushes after RR?

[Roadstar]

100NL

Hero 100
TAG 100
30/10 player 75

preflop hero has A[img]/images/graemlins/diamond.gif[/img]K[img]/images/graemlins/club.gif[/img] in SB

folds to TAG who raises to $4, 30/10 calls OTB, Hero reraises to $16.50, TAG ponders and calls, button pushes, Hero pushes?

I don't know what exactly the button could be representing here, and frankly not a whole lot, maybe 77-TT or something like that at best, so automatic push on my part? Consideration for TAG's range?

Thanks