just an anecdote, but Dsthen 8 had facial tics starting in 1st grade and getting worse by 2nd.

When we pulled him out of PS the tics vanished. And they haven't returned.

In HIS case they were undoubtedly due exclusively to stress. Prior to this resolution, however we had been considering Tourettes, ADHD and other "tranistory facial tics of childhood"

Interesting stuff, stress!