I haven't had the same smell again even though I've towed up the same hill with the same trailer and at the same speed. I'm thinking that it might have just been residual paints or coatings from the factory that was burnt off. Judging by the pristine shape of the receiver hitch I doubt that it has ever been used to pull anything before and that it probably hasn't ever gotten up to that temperature before. That's my best guess anyway.