Well whats interesting is the maintenance effected more then one plant over a very wide region.
I was not up at the time but it would have been a VERY short interruption. The few mins Alertra down/up is at the lower limit of its detection so it might have been down for seconds. Maybe it was just a big wide DHCP lease renewal.
Ive just never seen that in my 3 years of monitoring in multiple cities. It was odd. A whole region rebooting at the same time was odd.