Perhaps related to the fall and the head/eye damage, then?
I know the aged often start to leave their mouth open more and also flick the tongue out and back in, with some frequency.
My question, which I haven't really gotten an answer to, is at what point does plain ol' mental psychotic insanity become a factor? I'll ax that question again the next time it comes up.
Particularly the mouth-smacking is something that a talented therapist will make note of, along with head bobbing or hand tremors or other things that you or I would call "ticks".