Hey all,
I took the dog out a minute ago and heard my 4runner humming. Sounded like a small air compressor running... This got my attention right away. It was coming from the rear end, in the area of the spare tire. But I couldn't pinpoint it for the spare being in the way.

I didn't want to waste time lowering spare in case it was causing damage.

I started the truck, no strange startup or sounds. Turned it off and noise was gone.

Drove it up the road, all seems ok.

I drove in town and back today, first snowfall. Nothing crazy.

Only mods on rear end are; breather kit on transfercase, e-locker. And understating a few months ago. Fluid film.

My rig is a 2016 t4r, trail. About 17,000 km on it.

Truck hasn't been running for a few hours before hearing the noise.

Here is a link to a short video of noise
https://youtu.be/vcDEB8MnrEs

Any feedback would be greatly appreciated. It's stressing me out...
Ps I'm clearly no mechanic, so bare with me if this is something normal... I've never had this happen on any vehicle that I've noticed in almost 25 years of driving.

noise comming from the rear of my 4runner limited