Hey, I may have found something. I did not manage to take a picture, since I wasn't paying the most attention to my game, but I know what happened.
I was in a trainer battle and my opponent's Pokemon used Stealth Rock. I then KO'd that Pokemon, and got the message "the rocks faded away" or similar.
I'm fighting a Hiker in Terminus cave, his Boldore has Stealth Rock. This might reconcile why someone posted that Stealth Rock disappeared after 3 turns, while someone else disagreed.
This should be fairly easy to test, fortunately. Just make sure there is a Pokemon to come after the Stealth Rocker, I suppose.