It is being reported that due to human error (and the fact that the USPS did not have a POS machine at their NAPEX sales counter), the USPS inadvertently released the West Virginia Statehood Stamps on June 2, 2013 instead of the correct date of June 20, 2013.
As a result, some pre-dated first day covers were created by some enterprising collectors, as shown here:

It will be interesting to see what (if any) of these covers make it to
ebay (or other auction sites) and what kind of a premium sellers will place on the item.
Personally, I doubt the error is going to make any collector rich, but it just goes to show that first day of issue mistakes do happen.