I think you should just send her a message on Facebook and say, "How weird--those photos are tagged that we're in CHINA! Isn't that strange? I know it's not important, but it's showing up on my timeline that I went to China. Can you fix it?"
What's the big deal?
Just tell her, and then say, "it's bugging me--silly, I know, in the scheme of things, but would you fix it for me?"