Gorilla Glass is scratch resistant not scratch proof. See quote from their website:
"Gorilla Glass 3 with Native Damage Resistance enables improved damage resistance and toughness. This new glass composition helps prevent the deep scratches that can lead to glass failure. The result is improved scratch resistance, reduced scratch visibility and improved retained strength if a scratch occurs."
For this reason I use a screen protector on mine.
I've had mine since early March. No screen protector. No cover except Type Cover. I admit it. I not only use what I buy but I'm a tad abusive. I carry it a lot under my arm when my hands are full. Carry my wedge mouse in my pocket. I'm a believer in convenience. I don't like to "unpack" when I get somewhere. Not a scratch anywhere. Lovin' my SP.
OK, I had the same issue with my type cover. There was a grain of sand embedded in the type cover where your palm rests when I purchased it. Since the cover slides on the glass, it makes a v shaped scratch. I removed that grain using a flat screw driver so the damage is not noticeable. I did what most of you would do, applied a ZAG screen protector. I use Corel Painter 12, so wanted to forgo the screen protector but, oh well!