Since the Glass Break Sensor works based on sound, there are a couple of factors to consider if the sensor has gone off accidentally:
Ensure it not nearby any source of white noise, fan, motor, air vent, etc. Constant activation of the speaker can send a false positive.
Excessively loud noises in the same area as the sensor can cause a false positive; known examples are kids screaming, pet birds, construction being done on the outside of the house (roofing)- although it ultimately depends on the placement of the sensor and acoustics in the room.
Check to make sure the sensitivity setting (located on the inside of the device) is only as strong as needed. For example, if the window you are protecting is 10 ft away, make sure the setting is set to “MEDIUM (13 FT)” and not “MAX (20 FT)”. Smaller protected areas are less prone to false alarms than larger ones.