Hubitat update failed with Zigbee network down

Last night, my Hubitat Android Dashboard alerted me to an HE update. Having nothing better todo - I backedup and ran it.
A few minutes later, my HE was back up and running but I had a system message in the top right corner. Clicking it said 'Zigbee Network down'.

This was a first. I've done upgrades many many times and never have seen this before. When I went to the http://hubitat/hub/zigbeeInfo page - it showed Channel 11. I don't use 11 I use 15, and have for a very long time. I clicked on the drop down changing it to 15 and pushed changed channel. It came back with '11'. I repeated the attempts to change it. All Zigbee devices were down (Alexa would ding but nothing would change, no motion updates etc).
I went to settings page and pushed Reboot. After the obligatory few minutes - the hub came back online and things returned to normal. Zigbee details said Channel 15 again.
I didn't take any log snaps to offer here.

If everything seems OK now I'd keep an eye on it but chalk it up to experience. I have had the zigbee radio shut down when there was a misbehaving app overtaxing the CPU, but in that case a reboot only solved the problem for a few min. If it's been overnight you may be just fine. I've also seen recommendations to shut down cleanly, remove power from the unit (avoid pulling out the micro usb connector - do it from the other end), wait a few min, and power the whole thing back up. That gives the radio a chance to reset. But if it's working now it doesn't seem like you need to take that step.