What happened to /check/referer ?

Just when I discovered the validator and added the check/referer link to 
all my pages, then I run it through the link checker and get:

http://validator.w3.org/check/referer redirected to
http://validator.w3.org/

What to do: You should update the link.

HTTP Code returned: 301 -> 200
HTTP Message: Moved Permanently -> OK

What happened?

Thanks