Blogger etiquette

I was recently going through my old blog postings, and I found a thoughtful and positive comment by "Sarah" dated September 16, 2008. The original post was about research that purports to show that students learn mathematics better from abstract models rather than concrete ones. In the comment, Sarah apologizes for responding so late. (I'm not sure when the original post was; sometime in Summer 2008.) This is probably why I missed it.

Although I didn't have too much to add to what she said, I wanted to at least acknowledge her comment. I was able to visit her Blogger profile and her two blogs, but neither blog is terribly current and I would feel odd leaving my comment attached to a totally unrelated topic. However, if I were to leave the comment where logic dictates--on this blog, next to the original comment--it seems clear she would never see it.

I'd appreciate suggestions as to how to deal with this type of situation.