Self-Reboot After Firmware Update?

Black Hole

May contain traces of nut
I revised my out-stationed HDR today, from 1.02.20/2.xx to 1.02.20/3.10. I rebooted with the UPD plugged in, and the download stage started, then whipped out the UPD when the programming stage started and watched it progress to 90% and stall, then went out and left it to its own devices.

Normally one expects to have to put it into standby when it reaches 100%, at which point it restarts.

When I came back to it an hour or so later, it had restarted without intervention. Weird. Anybody else?