It's the mystery of the unravelling toilet paper. I don't know how it happens. I could understand if l had my toilet paper on a normal toilet dispenser like most people have in homes, you know the one, where the toilet paper is suspended on the wall on that little spring loaded role holder.
I have mine sitting on the wood that is over my tub, sitting straight up and down, there is no rolling action. If l don't move it when l drive, l will come back to find it still sitting up proper, but unravelled like l had a crazy little kitten that had played with it for hours. And as you saw yesterday, my cats are so far past playing with toilet paper rolls, and pretty much don't move from their assigned seating when travelling.
If the roll moved around so much you would think l would see it shooting up the isle when l drive, but that's not it. It's a mystery l tell ya!