No way were you over reacting.
I take Poppy to the pet store with me and it bugs me when someone just strolls over and starts stroking her, especially when im holding her which is 90% of the time because she will try and pick toys/treats off the shelves LOL.
It is just so rude! people should use their manners and ask if its okay first.
But I dont think I could have kept my mouth shut if someone tried to pick her up! I just think that it crossing the line. If someone tried to pick Poppy up she would be scared and wriggle, what if they dropped her because she was wriggling? Nope nobody will be picking Poppy up. Next time tell them straight.