in all honesty i have it too on mine and it could definitely be the auto focus lense. I dont see whats wrong with it if it rattles a little bit though. Its not like its the worst thing in the world. Its a phone its not gonna be perfect forever. Don't be OCD over something as simple as a little rattle. If your car makes a slight rattle going over a bump after driving it 60,000 miles do you take it back to the dealer and tell them you want a new one? No, so just enjoy what you have, you'll all get a new one next june or july just like i plan on doing and then you'll have something new to complain about. Maybe rather than the screen being too yellow it'll be too blue, and rather than having the 15 MP camera it'll only have a 5 MP camera instead. Try to return it, but if you don't get a new one then just relax about it. It's not as big of a deal as you think