No idea. I wouldnt worry about it until it gets worse. If it even does. Cuz at this point your drive yourself crazy tryin yo figure it out LOL. And if you wanna fix it get them dice out and roll em . But im pretty sure my truck does it. Ive got a faint grinding/ rubbing around 35-40 mph. Sounds likr trans related. But my old megacab did the same thing.