Has anyone had any difficulties with Applecare warranty replacement/service with an iPhone 4 that had a 3rd-party back? I want to use a Material 6 wood back (beautiful, by the way), and it looks like an easy enough swap, but it won't be worth it if Apple somehow cares if an issues comes up with the phone that isn't related to the back. I know I can easily reinstall the original back, and that you can get OEM backs if you damage the original one (so Apple probably sees those all the time), but since I just got my iPhone 4S and the Applecare+ warranty, I don't want to do anything that would risk coverage. I guess I could imagine them looking at the pentalobe screws and claiming that they look turned, and that I must have somehow fiddled with the inside of the phone. My recollection is that a manufacturer generally cannot decline a warranty claim for a modification that has nothing to do with what went wrong with the product, but I'm not sure here. Thanks in advance.