Losing devices without exclusion

Can someone explain how can a device get excluded from a hub without doing a force delete or exclusion? I thought once you pair it to a hub. The only way is unpaired or force delete it. 2 of my GE switches showed up this morning as new devices.

Unfortunately GE switches are known for falling off the network. Nothing to do with smartthings, you find the same complaints on boards for other zwave controllers.

It could just be a coincidence, or maybe it has something to do with smart things but the first thing I would try is just to power cycle the devices at the circuit breaker.