I have a tiny scratch on the gorilla glass (approx 2 mm). I got my preorder on Friday and used it for a couple runs and everyday wear over the weekend. Noticed the tiny scratch Monday AM. I can probably buff it out, you can barely feel it as you drag a fingernail over it. Went to the MS Kiosk on Monday afternoon and got a screen protector.
I have scratched gorilla glass in the past too (Motoactive GPS watch). Not sure how I scratched in either case, not hard hits on anything. I do wear the Band in the face down position.