Why would a 3560CX reboot EXACTLY every 6 hours?

I've got a 3560CX-12PD which has the peculiar habit of rebooting every 6 hours. EXACTLY every 6 hours.

Last configuration change at 06:28:09 EST Wed Mar 7 2018 Last configuration change at 12:28:13 EST Wed Mar 7 2018 Last configuration change at 18:28:10 EST Wed Mar 7 2018 Last configuration change at 00:28:09 EST Thu Mar 8 2018 Last configuration change at 06:28:08 EST Thu Mar 8 2018 Last configuration change at 12:28:07 EST Thu Mar 8 2018 

It's not in a high-use area, so there aren't any complaints, but I noticed it because I started logging config changes and every 6 hours I'm getting a new config dump and the only thing that has changed is the "Last configuration change at..." line.

If I look at the current uptime then that plus the "last config change" time almost perfectly equals the current time.

The last reload reason is "power-on". I've had devices with bad power supplies that have randomly rebooted but never in 6 hours intervals.

Any thoughts?