When you saliva glands get inflamed, it will do that. Before I started parasite cleansing, my saliva glands would go into spasms and spew saliva into my mouth. It didn't take anything to set them off. That cleared up once I did my first Humaworm cleanse, and I haven't had that happen now in months.
Since I have strongyloides, and they go everywhere, I just figured they were in those glands, probably got in there when I coughed some larvae up into my mouth.