If you are currently seeing a warning in Google Webmaster Tools that reads, “Invalid XML tag,” don’t worry. There are many webmasters reporting the issue and Google has confirmed it is a bug. Google said in an announcement post:

I personally saw this error presented on a site that was not Blogspot or Blogger on Thursday or Friday and the error is now gone.

Googler, JohnMu said:

Forum discussion at two Google Webmaster Help.