I had the same thing happen after copying and pasting shortcode from the documentation. There are some line break characters that caused an error when pasted into WordPress, causing it to default to http://bueltge.de/feed/.
If you paste the code into a plain text editor like Notepad, you can see the line breaks and delete them before copying it back into WordPress. This probably isn’t helpful for you any more, but hopefully it helps the next person that runs into this problem!
