I have noticed when sitting in truck after arriving, a click sound after shutting off engine and radio turns off. The sound seemingly comes from dash area on drivers side. It happened well after everything has turned off.
It's just modules shutting down, perfectly normal. It also will happen if you just open and close the door even if it wasn't started. I go out on lunch to nap in my truck (no start up) and a few minutes later the click down wakes me!