I think that you probably caught him in time before he ate any glass. I would just keep an eye on him for the next couple of days. If you notice and behavioral/physical changes call the vet!

About 5 years ago felice swallowed a sewing needle with thread attached I called the vet and he said to feed her bread and milk to push it down/coat the stomach. And to look through her poop to see if she passed it Till this day I never found the needle... I'm assuming she passed it becasue she's never had a problem from it.