Let me start off by saying I have had the 4s since October. It was perfectly flawless, than I foolishly sold it to go to Verizon. Then seeing how I preferred AT&T I went back to them. Picked up a brand new sealed 4s on eBay. I know the camera lens is suppose to have a small rattle to it as it has moving parts inside. That's not what I'm concerned about though, I notice my iPhone also rattles when I shake it. I can produce the camera rattle only when lightly tapping it. I just want to make sure my phone is normal. I then hold down the power button and slightly shake it and get NO rattle. I'm thinking this is normal and a piece isn't loose in the phone. In a very quit room when going from portrait mode to landscape mode you can hear the slight "moving part" inside. Its very, very faint but THERE.
Called up Apple and asked them and they said its not normal and my only option was to take it to a store or be sent a refurbished phone which they thoroughly test and is very rare to find an issue with.
I'm waiting to for my friend to bring his 4s over so I can thoroughly test his.