What to use to fasten the screen to the surround?

The battery replacement worked OK but the screen separated from the plastic surround while I was removing it. It's back in place now but I fear that the screen will be dislodged while in a pocket etc.

There seemed to be a very small amount of "stretchy" glue at the bottom of the screen, between the screen back and the surround (alongside the home button). Should I use some glue there to hold the screen in to the surround? Maybe a bit at the top also? And what should I use?