So I've heard that if the back of your iPhone 4 gets scratched, you can bring it into an Apple store and they will replace the back of the iPhone for free, but only once, and after that one time, the back replacements will then cost $29 every time you want it replaced. Is this true? Do they actually do this? The back of my iPhone 4 has a couple of semi-deep scratches and if I can get a free back replacement that'd be great! Thanks in advance!