Do you not see anything obvious because you don't think the information is sensitive?
It's just warning you that the string sent by the browser POST can be read by anybody with access to the browser (or anyone in between it and the server, if they care to look) and that you should use SSL if there's anything sensitive. The scanner can't really tell if the data sent is sensitive. If you communicate with the user over SSL then the warning should go away. It may not be worth it, though it might make it at least a little harder to exploit the XSS vulnerabilities pointed out in your other post.