Dave Cain posted on Google+ that his client received an unnatural link warning via Google Webmaster Tools and one of the two examples given was a link he has from DMOZ, the Open Directory Project. Yea, one of the oldest web directories online, which was once upon cited as a good link to have by Google themselves.
Before I get too far in, I wanted to say Google said that example link, the DMOZ one, is a mistake and should not have been given as an example.
Google's John Mueller said, "that particular DMOZ/ODP link-example sounds like a mistake on our side."
This may be the second time we reported a natural link being called as unnatural by Google in a short period of time.
John does remind Dave that although that DMOZ link is natural the site still has a manual action and needs some link cleanup. John wrote:
Keep in mind that these are just examples -- fixing (or knowing that you can ignore) one of them, doesn't mean that there's nothing else to fix. With that in mind, I'd still double-check to see if there are other issues before submitting a reconsideration request, so that you're a bit more certain that things are really resolved (otherwise it's just a bit of time wasted with back & forth).
On the topic of links from DMOZ, in a fairly recent poll, only 13% said these links matter much.
That being said, it is interesting to see a Google accidentally label a link from DMOZ as unnatural. I wonder if it was a newbie Googler who didn't know what DMOZ was or a typo of some sorts. The thing is, Google seems to really dislike low-quality directories, so beware.
Forum discussion at Google+.