Chirping sound when closing door?

[Nillaz]

Hey guys can anyone tell me if when you unlock the car and get in do you hear a high pitched chirping sound that lasts for about 5 seconds when you close the door? This has been happening for a couple months, and I have the car in for service at Nissan right now and they are telling me it is normal. They say it's a warning to let me know that the fob is in the car and it's designed so that you don't accidentally lock your keys in the car.

I think they're bullshitting me as it doesn't make any sense. If the chirp goes off when you close the door then you have already locked your key in the vehicle, rendering the warning useless. It also only happens when I get in the car and close the door before I start it, not when I shut it off and get out. I could be wrong though, so any insight from our oh so knowledgeable forum members would be much appreciated!