I'm very aware of my hands.
I close them, carefully, deliberately, so that my muscles pull my skin taught and the veins on the back stand out, bluish. I stretch them out; thumb to pinky I can reach an octave and a half, though I'd never play much more than an octave. I turn them over, I pop my thumb out, I crack my knuckles, each one, separately. I practice the sign language alphabet. I wreck my nails.
It's not something I do thoughtlessly; to the contrary, I find that it is only when I really think about my hands that I bother doing it at all. I'm sitting somewhere, in a car, maybe, or at a desk, or at a restaurant, and suddenly I'm thinking about my hands and opening them and closing them and wrecking my nails.
I could say I'm doing it to confirm that they're still there, but I'm not. I could say I'm admiring the design, examining the handiwork that went into making me the evolutionary miracle that I am, or that I want to really mean it when I say I know something like the back of my hand, but if you really quizzed me I doubt I could tell you what the back of my hands really looked like. I'm not testing out muscles; I'm not practicing piano. I'm really just very aware of my hands, and so it feels natural to move them around.
I like to think of things as endearing. Little things, like stuttering and freckles and constantly-crooked glasses, looking for the perfect word, or having a weird laugh, or spontaneous dancing. They seem endearing. I guess I sort of hope that my hand thing is endearing.
Don't tell me if it isn't.