I got my iPhone 5 last Friday, and I noticed while laying in bed that if I hold the phone so the screen is facing down towards me while laying on my back, and the camera is pointed towards my ceiling, whenever the phone vibrates it's followed by a slight rattle noise. It sounds like it's coming from the camera lens, and when I put the phone so the camera lens is facing down, I don't really hear the noise anymore... anyone else experiencing this? Is it normal or do I gotta get it replaced?