beeping under left side of dash

[remj]

I have a 2002 malibu. When idling in park i hear first one beep,
then after 6-7 seconds 2 beeps, 6-7 seconds 3 beeps, 6-7 seconds 4 beeps
no indicator lights are on, sound like it's coming for left side near where the
emergency break is
Is this hazardous?

[remj]

Rear Seat was folded down..probably caused the beeping..seatbelt related?
Who knows.dealer said there was nothing in my car that could make that sound. Thanks Chevy!