When I am standing still in a public place, I never know what to do with my hands. They need to be doing something. So I will hold a small object (usually car keys) in my left hand, form a 'u' with the thumb and forefinger of my right hand, and bounce the end of the object back and forth rapidly between those fingers. I have to make a conscious effort to stop, but after a few seconds I feel very anxious and have to continue. To me this seems very close to your finger-twitching. I have just recently self-diagnosed with AS, and have wondered if this might be a form of stimming. At some point I would like to get a professional diagnosis and ask about this, but if anyone can enlighten me in the meantime, it would be most appreciated.
Please be careful with the switchblade, OK?