I can't speak for adults, but many children with autism seek pressure and need various sensory input. Brushing isn't all that unusual, and some kids actually will request brushing. There was a time when my daughter would bring brushes to us (she's non-verbal) to request it. Sometimes she'll want pressure to her face and head, or to be squeezed.
Finding the right balance of "stim" is really important to people with Autism. Too much or too little creates a panic. Temple Grandin's Hug Machine (https://en.wikipedia.org/wiki/Hug_machine) is another good example. This was a hard concept to grasp growing up in the 80's with a severely autistic younger brother, but became clear in later years when I worked at group home. My experiences were very similar to the OP.
