I'm planning to get a case for my 64gb, most likely the incipio feather. Do I also need to put on a back protector as well? This is my first iphone so I'm not sure. I'd heard some people say the back of their phones got scratched even with a case because of dust getting inside. I would never have considered putting something on the back since it will be in a case, but I also don't want it to get scratched. Thoughts?