It may not have any connection and I could have misunderstood but I was told by someone with a little practical experience of patents that the US system differs from our own ref dating. In the UK a provisional patent can be filed and then after a period of time searches and challenges are made out and examined. If all is well the patent is granted and protection is backdated to the original application. In the US the system is different regarding timing and dates. Searches and challenges are examined first and if all is ok the patent granted and protection given from the date of that approval.