Validator yields error when type="text/css" not specified.

Whenever the CSS validator uses CSS inside <style> tags (as opposed to
giving the validator raw CSS data), if I do not specify type="text/css" in
the <style> tag, I receive an error: "Unrecognized link element or
xml-stylesheet PI."

Granted, XHTML5's specification is not yet complete, but it does say that if
a "type" attribute for the <style> tag is not given, then it defaults to
"text/css", so the two cases should yield an identical result.