CSS Validator Error (font-stretch)?

Hi,
Untouched parts of a previously css validated style sheet in use for
some years are now being flagged as follows:

	Property font-stretch doesn't exist : semi-condensed
	Property font-stretch doesn't exist : narrower

I believe 'font-stretch' still to be valid css2 - so I assume that
something in the validator has changed.

I am testing by local file upload via
http://jigsaw.w3.org/css-validator/ - and I have crossed checked that
this has not been caused by changes in other parts of my css sheet by
the direct input of the fragment

	.nav { font-stretch: semi-condensed ; }

Which again results in the doesn't exist message!

Comments please.

Regards James