This is what I'm talking about. The dynamic hair is grown on primitives hidden inside the head. But there are "strays" not connected to the object they are growing on.

I talked to Tiny about it years ago. It was a problem he encountered while creating his furry cats. He said it had something to do with strands at the edge of polys, or something like that. I think he fixed it by making sure there were no strands at certain places.