Sites in Webmaster Tools

I have my current sitemaps (wordpress etc) showing on Webmaster Tools under:

Code:

www.xxxx.co.uk

Having added vbseo, I've now an alert saying:
You're also a verified owner of these sites. Would you like to add them to your Webmaster Tools account?

Code:

* xxxx.co.uk

Should I just add it or should it have the www. prefix?

I received the same thing today. I added them. They were empty of any data, so i deleted them. I would suggest clicking no. It looks like a google hiccup.

Just make sure you have
[How to] Setup www.yourdomain.com or yourdomain.com (www vs. non-www) - With .htaccess 301 redirects - vBulletin SEO Forums
running correctly.