I've had this happen once, and the Apple store replaced the screen no questions asked. I usually use a microfibre cloth between the screen and the keyboard thou

I've had this happen once, and the Apple store replaced the screen no questions asked. I usually use a microfibre cloth between the screen and the keyboard though. It's a problem with all (modern) laptops from what I can tell - my Thinkpad T480s suffers from it, though my X220 does not.