my cat does his. not the head thing tho. sometimes he leg twitches. since i have the same think (tiwtching leg) from time to time i didn't think much of it. mentioned it to the internist who didn't know either. if you are concerned go for full bloodwork to rule out anything
I have 1 beautiful DSH tabby. 15 years old.
(and one sweet piti. 1.5 years old)