This looks like an apache thing.... requests to directories that lack trailing slashes are typically '302 redirected' to a page with a trailing slash. i.e.

http://whatever.com/abc  => 302 => http://whatever.com/abc/
[download]

In this case if it is a POST, you'll lose your params (see POST redirect), but depending on your setup a METHOD=GET might be able to keep them.

-Blake