>> In case it's not clear, I was not editing said file when the system rebooted
>> I had exited normally, and yet I still get these annoyance emails.
>Are you doing this on a diskless client (i.e. with /var/tmp on NFS)?

No.

But it is a system on which I've done a number of upgrades, some source-only,
some binary, and so permissions may be off on some directory, or some obsolete
files may be present, or /etc/rc may have some arcana.