It turns out that the "Comment Publicly" question wasn't working the way it was supposed to. When your comments got to us for moderation, everything was marked as wanting to be public. Oops. I tried to figure out why, but I don't understand that part of Django well enough. I did make it so your choice is now saved correctly.
If anyone posted a comment that they wanted to be private, please post another comment telling us to make it so. I'm very sorry if your private comment was made public against your wishes. I'll test my software thoroughly next time.