I also find myself doing this when the panic is coming in strong. I think it's a way of doing something to keep yourself pre-occupied that also causes a routine, which can calm us. I also notice I will sit and rock back and forth without realizing I'm doing it when I get extremely anxious.
yes, i have to move, or if i am sitting i pick up a trinket from my daughter and just rub it , its a miracle theres anything left of it i rub so hard. my daughter also suffers from anxiety, she sits down and just rocks back and forth, i think whatever helps Kay