The alarm panel beeped and indicated loss of supervision. Seems odd since worked fine up until this happened. The sensor is about 40ft way & sensor wireless signal shows 4/5 bars. I simply opened the door and closed it and seems ok now. Any idea what would cause that ?
A temporary loss of supervision could be caused by any number of things. Anything that can causer interference with the sensors wireless signal can cause a sensor to report a supervisory error. Some things that can cause interference are a large number of other sensors(>40), other devices using the the same frequency as the sensors, a large number of dense building materials (Brick, Metal, etc.) between the panel and sensor.
Generally speaking, it shouldn’t be anything to worry about unless it starts to happen on a regular basis.