Sorry, did you just shake my juice?

Is it weird when a person who is selling you an orange juice shakes it for you? The girl that was serving me today gave it a real shake and I didn’t know whether to yell “STOP IT! That’s my job!” and snatch it out her hand like I’m disgusted. It wasn’t like she was killing time either, she stopped everything else to do it. She gave it a good 10 second shake, and she almost started using two arms she was that much into it. Yes, I had a slow day.