Which goes to show how every iPhone will differ in specification and tolerance, which is all relative, but variable. What you could do, is make a Genius appointment and have Apple inspect it. However, if you exchange it, then you have the possibility of finding other defects with dust, etc. If you think it's tolerable, then I would keep it as long as you deem it Suitable. But no to iPhones will share the same tolerances with buttons, mute switches, dust under the canes lens cover, etc.