I bought a secondhand iPhone x (Space Gray), first i didn't notice that the stainless steel got rainbow color like blue,yellowish,rust, but when your'e at indoor its not noticeable, but when i go outside it really exposed the rainbow colors on the stainless band side to side and on the bottom of grills too only slight at bottom. Is this normal?. or there's a way to remove the stain on steel band. The phone age is already 1 year and 8 months. Everything is okay not really hot when using except when your taking picture outside for too long. Should i worried? Sorry i cant take an actual picture now.