Not how you want to find your computer room!
Yup, that's a glass door spontaneously shattered overnight. Certainly the first time I've seen anything like this.
(And it's obviously shattered rather than fell out - the distribution of glass indicates that it's dropped vertically. That was a mess to clear up, let me tell you! Fortunately safety glass tends not to generate large sharp pieces, although there were a lot of nasty dust-like shards.)