Wow, beautiful truck and location.
I have yet to buy winter tires for my 22 XL hybrid, and I do live in snow country. I eventually will, but haven't felt rushwd. To do it, the truck does OK with the stock tires.
I heard that same noise for the first time this week. It was hard to determine where it is coming from, and (like you) I am uncertain whether the engine was on or not at the time.
It almost certainly has nothing to do with the oil change. Most likely an unintentional change in the other variables, such as driving style, speeds, wind direction and speed, temperatures, tire air pressure, etc.
Edit: Did they do any other work on the vehicle?
Nope. If I were buying today, with the price difference between configurations, I would be buying the 2wd.
I live in snow country, and 2wd is quite adequate. The tow limitation is likewise a non-issue for me.
Yes, I am a cheap XL hybrid owner. So, I'll keep my money, but thanks for the...