never had it happen with any of ours.
One home we clean has a plug in CO detector
(plugs into a regular wall outlet)
They keep plugged in , in the hallway.
You'd think if pre-spray would make it beep, it's location near the floor in a small area like a hall would would set it off
do you run a TM?
are you sure it's not your TM or van?
It doesn't take much to set them off
..L.T.A.