I noticed when I shook my iPhone 4 the lock button on the top has a rattle noise. The button doesn't actually rattle, but whatever is under it does. When I hold down the lock button and then shake it there is no rattle. Does anybody else have this? I did drop the phone a couple of times, but I have the Speck PixelSkin HD on it. Didn't know if this was pre or post drop.