Welcome to the club. There any quite a few people who have this problem. Or club is growing and will keep growing.
Jokes aside, the Nokia 8 is a s**t product. Even worse is only how/that Nokia has chosen to handle (read: ignore) this serious problem with their so-called flagship phones (and is continuing to do so). You're in for a wild ride. The following will happen now
1) you'll bring it back to the shop, claim your warranty.
2) wait several weeks.
3) get your phone back and realize hours later it's not fixed at all.
4) bring it back again.
5) wait a few weeks again.
6) get it back again.
7) check in the store (!) And optionally 7a and 7b don't accept it and wait again. (I'm not sure what's next, this is where I stand now, I don't know this part of the game yet but I'm pretty sure I know the drill by now.)
In the meantime your enthusiasm from the first days will quickly descend into wondering and disbelief, then disappointment, then furious anger. I call it the 4 stages of Nokia experience. While you are occupied jumping through the rings Nokia has provided for you (for free, nice guys), you'll be checking in this forum (or others) for "burn in" or "screen retention" and so on and realize your not alone. A few weeks later someone else will have the same problem and you'll greet him with "welcome to the club". (Possibly from a phone not by Nokia.)