Yepperdoodles. Pretty common back then as the base or additive to the plaster matrix, as it was easy to add into the mix and allowed you more fun dimensional stuff for strength (and of course, fireproofing). Like Cobbler said, it's also in the plaster. Your choice is either don't touch it or have it abated, which is a PITA because you're legally supposed to have a licensed asbestos contrator do it.
Be glad... my folks place had asbestos shingle siding covering the hous we grew up in. Someone damaged the side of their house, and their choice was to try to locate more of this fine building material or pull it off. Back then abatement was a lot less restricted than it was today, how we did it could have gotten him in a world of ****, but he had us kids prybar it off and throw it away. Nowadays you'd get fined AND go to jail for that.
I remember the popcorn flocking with the "glitter" asbestos on ceilings - beautiful, oh so 60's groovy, and would fall off if you touched it. The house was too old to have it (thank God), but yeah, all my friends in newer houses had that stuff on the ceilings... to think I envied them.
