Basing it on my experience, this usually happens when your articles are buried down the search engine due to some penalties (with the recent Panda-Penguin update).
It happens when you overly promote in link building sites (possessing the same title and post summary).
You may try to analyze your traffic sources. If the 40 to 60 visits comprises of hubpages view, it usually happens because there will be a sharp increase during the first few days upon publishing the hub due to Hub Hopping of fellow hubs.
But if it's more from the search engine, then probably, the one I said earlier could explain the phenomenon.