My S7 edge has a very fine crack that goes from edge to edge horizontally. The only way you can feel it is if you rub your nail over it to feel that there is a groove. You can only see it when the screen isn't lit or when wearing the VR Gear. I don't mind it at all because it doesn't affect the functionality or the look of the phone.
How it happened was very odd to me. I was at a pool party and the phone was in my bathing suit's pocket. I usually put the phone in with the screen facing my thigh, but I was buzzed, so I could've did the opposite. I was sitting in the grotto and bumped the edge of it, which had some bricks and stones, pretty hard. It would've hurt if my phone didn't absorb the shock. I take my phone out shortly after and there was that crack.
Needless to say, no more showing off it's water resistant, I don't need water getting into the crack.