Power Outage - Window Sensors

We had a power outage yesterday for about 6 hours, the base station remained online and I had set my alarm to away, however when the power restored all of our window sensors sent notifications that they had just been closed. I'm wondering if anyone else has had this happen, and if the sensors stayed online with the base station during the outage? I didn't think to look at all the sensors during the outage on the app, just the base station.