hi, I am a long time "lurker" of MacRumors and finally had to register. I got an iPhone 4s on launch date to replace my aging 3g. I have noticed when it vibrates you hear a loud rattling sound almost as if there is a loose part inside. when you have a firm grip of the bottom right when it vibrates it does not make the sound. Also when you shake it you can hear a similar rattling sound, but does not go away when you grip it. My question is whether or not this is normal, and if not should it be of any concern. thanks edit: might i add, the sound i hear when shaking it sound like an autofocus lens or gyroscope(im not so concerned about this, when it vibrates you hear that sound AND another much louder vibrating sound.