You guys are just way to hard on people. It's about as common as anything else to have little scuff makes on the iPhone 6-6s/plus antenna bands. I mean really? This isn't user error all the time. Apples quality control is not there anymore, there are loads and loads of posts and threads about people Opening their boxes and finding scuffs, scratches, dead pixels, you name it.
@op....honestly if your not using a case on a phone like this, that's just asking for trouble. You can wear pants made of clouds from the heavens and you will still end up with hair line scratches. My advice, get a case and call it a day. Lol, the material inside the case can even scratch the device....is what it is man.