Is this the only place where you have found issues?
I'd be interested to hear why you are using the strict DOCTYPE? I did attempt to go down this path quite some time ago (around 3.3/3.4) but just found too many issues in validating and quirkyness in the various browsers. It was much easier to settle on the Transitional DOCTYPE.
Interestingly there is a school of thought that says that XHTML shouldn't be used for most sites and I'm coming around to this side of things.
XHTML is not for Beginners http://lachy.id.au/log/2005/12/xhtml-beginners
HTML vs. XHTML http://wiki.whatwg.org/wiki/HTML_vs._XHTML
I was testing XHTML 1.0 Strict for a template for a client (it's funny, because their marketing department wanted a STRICT mode... it's a long story...)
