Glad you got a good one. These issues can be really bad on certain phones. I had a diagonal black line that went from top left to bottom right that was visible on all gray backgrounds during normal use on apps like Amazon music. Apple tech saw it right away and I got it replaced. My current one is HORRIBLE. There is a bad pink shift on half the screen that gets even worse at the side edges of the screen. Happens on -slight- angling of the phone just by using it normally with one hand. I have tons of apps with white backgrounds and it is quite bad.This thread: When I tilt my phone and shake it while hanging upside down with one eye closed, I can barely see a pink hue on the left side. It's going back and this will be the seventh phone I returned.
I should have just returned my last one and re-ordered, now I am stuck in the exchange process. If I can't get this one exchanged I will just sell it and move on to another phone. I'm in the vast minority but I hate OLED. As much as I hated plasma before it but for different reasons. Several family members have various LG OLED TVs and I've used several OLED phones. I'd take bright whites of LCD / LED any day over pitch black blacks (I don't sit in a cave all day with my phone or TV) not to mention awful banding with OLED. Can't wait for OLED to be replaced by micro-LED, but who knows how that will go.