I was out of town for the weekend with family and returned last night to find that the hub had crashed. The UI was unavailable (connection refused) and no automations were working, but I was able to connect to the diagnostic port to reboot.
After reboot, the past logs showed no activity after 2:30am on Saturday morning (backups are set to run at 2:15 am) with no obvious indications of problems. Things seemed to be working as expected after the reboot.
This morning I did a backup and soft reset, and plan to update to the recent 2.3.135 (though there doesn't appear to be anything in the release notes that would impact this issue).