Hm, yeah that's weird. Autosaves wouldn't help here because it's not about state--we can already clearly see the saved state on the map there, it's about whatever caused it in the first place.
All the map memory does is keep a copy of whatever objects you last saw at that location, and it looks like you even went down each corridor a bit towards the door so it's not like it didn't have time to save/update this info in any way. And clearly you weren't using your Lrn.Terrain Scanner, so that couldn't have played a role...
No idea how to repeat this, and it hasn't come up before... I'm out of ideas, guess we just have to wait and see if and when this happens again.