HHR_SS_QC

I think my SS bcm has a problem. When i press the electric door lock button (with the door open), sometimes i hear 3 full chimes (ding ding ding), and sometimes i hear only 2 1/2 (ding ding di...). The door lock operate correctly though. Only the chime count seems affected. The car is like that since new.

Anyone here has had this problem? I had a Cobalt before, and there were always 3 chimes, when I pressed the door lock button with the door open.