Have a small part left over, what is it and where does it go?

This is a tiny little metal shield or something like that, about 5mm long and 2mm wide maybe. It is shown in one of the tiny screwdriver bit slots in the plastic tray that the tools come in, if that helps. Sorry about the crappy phone photo that I took with a clip-on close-up lens.

The part came out of the phone somehow while I was doing the battery replacement procedure and trying to get the phone apart. I've now changed the battery and am putting the phone back together, so need to know what to do with this part. Thanks ;). Paul