I just noticed the same thing and thought I was hacked. Yes, I am on a public network. It's a hotel network. I have sharing turned off, but this guy's library is still there. Any idea how to shut it off? Just because I can see his, can he see my library as well?
And I just found the answer. Under preferences in the General Tab, under the show category uncheck the box for 'Shared Libraries' that should get the stranger's name to disappear.