Unfortunately this happens in most low pixel density OLED screens, unless they are Super AMOLED Plus (or at least that’s how Samsung called the version of OLED with a traditional and regular RGB subpixel arrangement, I think they only used it in the Galaxy S II).

The diamond subpixel arrangement definitely minimizes this effect, but probably doesn’t work too well for low pixel density screens, since it’s primarily found on mobile phones.

Same happens to me, and seems to be pretty common with the OLED model. Something was redesigned around the button area probably.

For 99% of people seems to be a non defect, and I wouldn’t worry. In my case, I think I will return it, not because of the rattle itself, but the X button in particular is so loose that can be depressed diagonally, and can get stuck (I play a lot of retro games, and in general games that require smashing buttons, where it’s more likely to happen). Other than that, I could very well live with the rattle.

Same on mine. The rattle itself doesn’t bother me, but in the case of the X face button it’s just too loose, feels sticky at times. It can be easily depressed diagonally, and some times will not pop back up. I think I will get mine replaced.