I think it was the other way around and he didn’t take out the magazine, pulled the slide back and seeing a round eject thought the thing was cleared.
Saw my Mom’s husband do just that at the range once.
Lesson learned and never, ever forgot.
You like Chinese Food? I have a friend who has a restaurant and I’d like to take you.
It’s in Willow Glen. It’s called Sweet Mango and the owner is a real nice gal. She worked at the Taiwan for years and then opened this place with her husband two years ago.
Looking down the chamber after removing the mag helps.
That's a very common mistake, pull the slide back, check the chamber and see its empty, release the slide (now it just became loaded) then pull the magazine.
Happened to me once at home when I was showing a handgun to a friend. Fortunately my friend did what he was supposed to do, pull the slide, recheck the chamber and lo and behold, there's a cartridge in there. Scared the living crap out of me, and yes, that was a learning experience....... I still cringe when I think about it.