Device being replaced under Warranty. What counts as physical damage to phone?

I have a Samsung Active. I am being sent a replacement phone under warranty. My phone has been in a case and a glass screen protector. there is no damage to the glass. There is a small scratch on the corner of phone though. It is not deep. It is almost like like it has just been rubbed off due to friction. Is that enough for them to say it is defective? This phone really is in almost new condition. Thanks