Probably just years of dust behind the paneling. There is a better chance of lead paint on the walls than asbestos.
You can get a home test kit for lead from home depot or lowes. It is good to know what you are dealing with. And if it is lead paint on the wall don't panic, just use common sense when workng.
Plastic off rooms and clean all dust very well and wear the respirator.
If no lead I would still work clean.
It is more likely that there is horse hair in your plaster than asbestos (that's right horse hair)