http://validator.w3.org/check/referer redirecting to document root

The http://validator.w3.org/check/referer URL is being redirected to
http://validator.w3.org/.

I think this started to happen some time this morning (Sat AM in Australia - Fri PM in US).

I've checked this from several sites (including http://validator.w3.org/feedback.html) using a variety of browsers - all had the same result.

http://validator.w3.org/check?uri= is working OK.

The CSS validator http://jigsaw.w3.org/css-validator/check/referer is also OK.

I'd appreciate it if this could be fixed - I find it an invaluable tool.

Thanks in advance,

Ken Cotterill.