I try to assume the best about people who post clueless comments. They might be young, socially awkward, or coming from a different part of the Internet, where comments like that are considered acceptable. In any case, I wouldn't let yourself worry about it if it happens to you again in the future. It was awfully nice of you to post a polite response, but a comment that's way out of your comfort zone can be safely ignored. (Unless the comment is threatening, in which case, it needs to be reported.)