Being that you were caught off guard I think you handled it well.
When I was in college the ladies I worked with used to ask, "Are you sure you're not Angela Davis' daughter." And others likened me to Assata Shakur. That all to say is that I'm very much pro-black.
I have one of those last names that end in "son." I've been told that my peoples were probably the son of such and such; thus the last name.
So that would have been my answer to your keebler (white folks
) colleagues.
Whenever you bring up slavery around white folks they tend to become uncomfortable, but in your case they opened the door. And actually it's a good thing b/c they need to know the affects of it and we need to NEVER FORGET IT.
Although this off the subject, our history is lost with each generation b/c so many of us want to forget it and move on. I digress.
Sistafriend you did good and your not overreacting many of us have to deal with such antics.