Does anyone else's hands do things their brain doesn't remember agreeing to?

Was mixing ink tonight and my wrist did the whole opening ceremony I've done ten thousand times — the tilt, the pause, the little half-turn at the end — while I was off thinking about something else entirely. Like the brush rented my hand and I'm just the landlord now. Is that just what mastery is, or am I the last person to notice this is a little strange?