Microaggressions or... not

I had a good time paying attention to the #critlib session on microaggressions. Storify's here http://goo.gl/SR7Bg8 I do get that we tend to operate off of stereotypes in the worst possible ways, but could there be times when we simply should NOT be offended? I am now working with librarian who also has short gray hair and similarly-styled glasses. We're almost the same height and appear to be roughly the same age. We're both caucasian. Students mix us up. #notmicroaggression, right? If students mix up two staff members who look alike, is it possible that they really do look alike?? If you look like a student, should you be offended if someone thinks you're a student? How can they tell you have a different status? Even if you are sitting at a service point... What's the indication that you are a librarian and not a student assistant? I think there's a possibility that this might not fall under the heading of microaggression. Or.... ?