The same phone exhibits a couple small cracks, as shown here:
Just noticed that same crack on mine but I'm not going to return it, mainly because it might be from me. Do you think that crack is a defect or from dropping? It's not like those gray hairline cracks. Every other aspect of the phone is perfect and I don't want to risk getting another one with a light leak or some other defect (I've had bad luck with my other iPhones).
Edit: Just read your entire response about the crack, never mind then.