I think this is a common problem. Same thing is happening to my '11. Got customer service involved and still hasn't been fixed. 30K miles since mines been doing as you described. Ford keep my car for 5 days, drove it 35 miles and the light didn't come on for them. 2 days later it did and I called to try to take it in so they could run the codes since the light came on and they said no tech's available. Pretty frustrated myself.
Welcome to the forum as well. I’d like to get this reviewed for you. Please make another appointment with your dealer and PM me with your info as well.