I LOVE SPINNING. I love love lurve it. BUT it makes my hand hurt. The two joints of my thumb, mostly, and the biggest knuckle of my index finger sometimes as well. Also, at night, my smaller thumb knuckle pops in and out. I notice it when I wake up in the middle of the night. It's gotten to the point that I can't spin very often, and when I do it hurts for days afterward.
In my experience there are mainly two kinds of pain associated with activity - the good kind, where you worked out and your muscles hurt because they are lazy and haven't done anything and need to get in shape; and the bad kind that goes with repetitive stress injuries and suchlike. Unfortunately, I fear this is the latter kind. I've only been spinning since Christmas, when Adam gave me the spinning wheel, and I'm probably doing it wrong, since I learned from videos online and kind of figuring it out myself. I don't know any spinners in real life. I joined a spinning guild in the area and their next meeting is in April, which I definitely plan to attend so they can pay attention to the high maintenance newbie who is probably doing it wrong.