@mapsame,
First things first. It would have been nice of him to ask you, but he didn't. So get over it. Life is too short and this is a minor thing.
It would have been nice if they asked you directly, but they didn't. So get over it for the same reason above.
Seriously, this is a .00001 on a scale of 1 to 10.
Secondly, enjoy the fact that someone is coming over and cooking for you on a holiday.
I have a question for you.
If he or they had asked you, would you have said ok?
If the answer is yes, then the result would have been the same. You get a cooked meal. Why would you waste your energy feeling hurt if the end result of such an incredibly minor thing was the same?
If the answer is no, it wouldn't be ok, it's definately not too late to make a big stink by telling him, to tell them to cook the meal at their home.
Then, everyone get's to be upset, and not just you.
Happy Holidays, I'm pretty sure your Christmas will be great.
Next case.