ya or u can bend the terminals that hold your bulb in place in a bit so the light sits in there tighter and ya Just line the dome light housing with thin foam
remove the light.....next! Seriously though, if thats the only rattle that bothers you you've got issues. I hate my rear deck, hated it with 2 ported 1000w 12", hate it with the stock pioneer 10".
I put little permatex globs at the meeting points of the lens and the housing and let it dry overnight. It fits real snug and doesn't rattle or break down like foam.