I came to use my XE93 this evening when I noticed what I initially thought was a "bug" on the screen. I went to get a cloth to remove it, but alas it didn't shift. It is instead a small black mark on the screen. On further investigation I can see three such marks at various points on the screen. I'm about to drop John Lewis an email and then follow up with a phone call tomorrow. Any idea what might have caused these marks to appear?