Window question

[Slippery S14]

I recently picked up a s14 and it has a wierd thing with it. The passenger side rear quarterpanel window is not flush. it seems like something a rubber hammer could pop back in but i'm a bit concerned about breaking the glass. The area that has popped out is the back corner where it has the "pop-in grommet piece"

Any thoughts besides taking it to a window place? Has anyone had an issue like this before?

Thanks,Slip