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No, Google Webmaster tools do not list an error here. Its indeed an SEOmoz bug. Ryan, thanks for trying though!

Meta robots refers to the < meta name="robots" > tag at the page header level.  This is usually the case when a blog is set up with an SEO program like All In One SEO for example, where you can manually set which content is blocked.  It's common to block archives, tags, and other sections, in the theory that allowing these to be crawled could either cause duplicate content issues, or drain link value from the primary category navigation.