Should you make a deal out of it? Probably not. Next year you can remind her to let you know what she is fixing so you don't duplicate it. And hey, you will have more leftovers.
What used to drive me insane is that my SIL and I would each cook part of the dinner. We would set the time for dinner and I would plan everything to be ready then. Then they would call two hours early and say they are ready to eat and sitting at the table. I would try to explain it wouldn't be ready for awhile but the pressure was on.
While we are talking about TG, it's time for the annual TG letter from Awkward Family Photos:http://awkwardfamilyphotos.com/2009/11/26/awkward-family-story-the-thanksgiving-letter/