3 or 5 beeps after drivers side door opened (ignition turned off)

[mekelly]

I have a 2001 2WD Pathfinder with about 88,000 miles. My son told me that the security alarm has randomly starting going off over the last weeks or so. He said it's gone off maybe 3-4 times. Don't know if this is related but now when you open the drivers side door after you've shut off the ignition the car 'beeps' either 3 or 5 times. This isn't the chime like you've left the lights on or the keys in the ignition, it seems like it's beeping a diagnostic code. It's never done that before. Does anyone have any idea what that means?