New Tacoma - Hollow Whirring Sound

I have a 2015 Tacoma TRD Off-Road with about 2400 miles on it. Everything seemed great until a couple days ago when I began to notice a faint 'hollow whirring' sound seemingly coming from the passenger side of the truck. Seems more forward than rearward, but very hard to tell. It starts to become audible at around 35mph and gets slightly louder as I approach 45mph, after which it stays the same or quiets down again (partially because wind/road noise muffles it at higher speeds).

What the hell?

 

I have the same issue on my 2015 Tacoma, only at a higher speed. I'm still trying to get the dealership to do something about it, but nobody seems to know how to fix it. Any luck or suggestions?

 

Would that turn your frown upside down?