I saw some news story that was warning against people using scanners in parking lots, and getting your frequency (i guess) when you lock your car with your fob as you're walking away. It gave the advice of: if you see anyone standing around in the parking lot as you're getting out of our car, hit the "lock" button on your door rather than using your fob.
I didn't pay as much attention as I probably should have because I already only use my button on the door (since my fob is generally in my pocket).
Also, as someone who has had a car stolen the old fashioned way (with the steering column ripped out), I'd more than appreciate the less damage being done to the car as possible in case it's found