I went in to my local store to pick up a 5S today (which was out of stock). I was checking out the display models and noticed that most of them had dead pixels or dust behind the screen and even black lines across the display. Is this actually a common problem with the 5S? I know these things do happen but it just seemed a bit strange that so many of them had something wrong with the screen. I'm worried that I'll get a device with something wrong with. The display models will obviously be from one of the initial batches so hopefully Apple's quality has improved over the last few weeks.