Over 365 days of uptime, mother just suffered a kernel panic and died. The fine supporting staff at KDDI reset the computer for me, and mother came up sync’ed the soft RAID and went back to normal.
I have yet to figure out how to conduct a proper postmortem for OpenBSD, as both the hardware and the software are both very reliable (4 hours of down time over the last 12 months, previous outages were all due to human error) so there isn’t much need, but I am going to get to it eventually.