This happened to me too. I bought one in late 2015, but it has a 2012 serial. Furthermore it's in a colour which was only available for 2013.
With Fender, the serial number only dates the neck; it doesn't tell you when the guitar was actually put together. It could have then spent a while at a distributor, and at the dealer before finally being sold.
It's not concerned me at all. I think the value of any post 2012 American Standard would be based more on condition than age.