What made her freak out? Just the existence of the banner, or that she didn't realize Wikipedia needs funding from the public? How did she respond afterwards?
1. She had no clue who this guy was suddenly staring at her 2. Didn't know Wikipedia needs $
http://theoatmeal.com/blog/jimmy_wales
Note: Though I would normally not post these kinds of links, it's somewhat relevant to the topic at hand.