Hi Davy,
Yes, this looks like a good amendment to make to xmobile, we will discuss in more detail here today and let you (and other customers) know of the recommended changes. We've been researching the "official" word on this from Google and it seems to be good practice to include this response in the header, so we are happy to implement this:
https://developers.google.com/webmasters/smartphone-sites/details
we will keep you posted.
regards
W.