If there is any form of radar, laser, speed trap in the general area, your detection device should pick it up, regardless if you are the target or the vehicle to your front or side is the target. Worse, if its you and it's probably too late once your device goes off. A radar signal from a bank or store can set it off also.
Point to remember, if your device goes off and it never went off on that same stretch of road before...... "Something" is in the area, slow down and try to identify the source of the detection.