I got the error of "Submitted URL marked ‘noindex’" in google search console (former google webmasters). I have setup a node to mark threads as noindex if they meet some criteria.
The code doesn't really allow that to happen so I have to assume it's a false positive or referring to an old sitemap entry or the noindex happened since the sitemap was last built.
Does it identify the thread? Is that thread listed in your sitemap?