Unknown noise under the hood!

I have a newly acquired 2012 GMC Terrain, SLT2, FWD, four cylinder. I have discovered something my dealer has never heard of and knows nothing about, but says it must be normal!!!
With the engine (hot or cold) and ignition off, key removed, about 15 seconds after opening any door, rear hatch, or hood, a “clicking” sound starts up under the hood and lasts several seconds. The same thing happens again after you close the door, rear hatch, or hood!! Using my automotive stethoscope, I have traced the sound to the front cover of the automatic transmission where there is an electrical connection. It is very audible at that point.

This is not causing any problems, but I would really like to know what it is and if, in fact, it IS “normal”. If it is not normal, I need to get it repaired as soon as possible, as the car is still covered under GM’s Certified Pre-Owned vehicle warranty. My dealer rep. could actually hear the “clicking”, but was not concerned enough about it to even try to find out what it was!! He just told me it was normal!!

To begin with, have them demonstrate the same noise coming from a vehicle of the same year and powertrain.

" I have discovered something my dealer has never heard of and knows nothing about, but says it must be normal!!! "
I haven’t read anything so scary since “The Pit and the Pendulum”. Your tracing the sound with a mechanics’ stethoscope make you about 1000% more knowledgeable than the dealer person you spoke with.

Is this vehicle under warranty? If so, take it in with a formal, documented complaint so’s you get it on paper while you try to follow NYBo’s advice (if they happen to have another vehicle of the same make & model).

If it isn’t under warranty. have a reputable independent tranny shop listen to it and render an opinion.