Sim died suddenly and wasn't reaped

I just had a Sim die - there was no (obvious) cause of death, no notification that they were dying, and the grim reaper didn't appear. The Sim just turned into an urn and was removed from the household. I'm not sure what they were doing when they died because I was in 3x speed and not fully paying attention, but the urn was next to a murphy bed (99% sure they didn't sleep in it just before death because they were well rested and I hadn't told the Sim to sleep).

Has anyone else had this happen?

I've never seen it before. Not sure if it's a bug or just something I don't know about and I don't know how to re-create what happened. I started the save file just after today's update (and didn't turn mods back on) and did the Engaged In Conflict scenario.