Actually it gets worse over time. This malady has been a problem with my wife's '99 E46 for the past 4 years. Now it happens something like 1 of every 10 times she unlocks her car. She did try switching to her spare remote key which temporarily solved the problem, but after about a year, occurrences were as frequent as before. My guess is the central locking control box that pulses the door actuators is probably the culprit. I forget the BMW acronym that describes the box.

It doesn't seem to bother my wife. She's grown accustomed to the problem.