By itself, it's a sign of a kid flapping their hands. Might be a sign of Scots, Irish, or Italian blood.
If you see that, and a lot of social mistakes that are not age-appropriate, and a poor ability to tolerate frustration, and avoidance of eye contact, and, and, and, and, and...
...then it might be a sign of something.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"