I had this problem corrected on my truck by the Brooklyn SC. They told me there was some rubber tubing that the louvers were rubbing against, which they re-routed. I haven’t had the problem since.
When I opened my case I did use the “vampire’s coffin” analogy in the description . The Service Manager in Brooklyn said that got some laughs when the techs watched the video I included.
My current guess is there are some nylon bushings causing the issue. Unintuitively, nylon expands under colder temperatures. I think as we are entering autumn, that’s why it’s starting to pop up now.
edit: this might be a crappy hypothesis. I recall reading about this nylon property on the internet, but I could not find a good reference today for it. Plus it’s pretty hot here today and it’s creaking anyway.
i also had this problem. I walked into my closed garage with my cell phone to get something in the freezer. The truck woke up and groaned. It was so loud it startled me. I thought my garage door spring was about to break .
I originally thought it was the suspension too until I saw the louver moving.
I took it into service and they lubed it. the service rep said this is a common problem. I haven't heard it since.