Geeezzz, I know this thread is old, but I am a bit taken aback by some of the replies here!
No you're not over reacting! Hands are part of your body, people shouldn't just assume they can use them. Afterall if you'd grabbed his hand to wipe yourself after using the toilet or to pick your nose or something I doubt he'd be too pleased about it. (Im not suggesting that you would of course, lol!!! It's just and example) I'd be pissed off too if anyone did that to me. I think you reacted fine, I would have done the same! (-: