I purchased my 6s less than a month ago and when the screen is off I see a weird like circle almost like the coating is off. It's where I use my thumb the most to type I think but it's a weird circle smudge or what have you. It isn't evident anywhere else on the screen. Should I return or is this normal? I don't want a refurb I want a new one if this isn't right. It hasn't even been a month.