Muscle Memory? Interesting Observation

When I type my passwords in on the iPhone for different accounts I have scattered all over the internet, I sometimes find myself having to close my eyes and type the password out on an imagined kwerty keyboard. I can't remember the password to type it into the smaller format keyboard of the iPhone until I do it in my mind "old style". Isn't that hilarious? I wonder what that is? It makes me wonder if my passwords now reside more in my fingers sometimes, and am I actively thinking when I quickly type one in, or does it just flow out of my hands? Is that possible? Do our nerves remember motion to that extent? Is that what the ability to type is? Gods, I'm ignorant. :)