Men! I have been with my partner for 20 years and still sometimes he does things just assuming that I am in agreement with what he wants, they think we are mind readers!
I remember when we first met, he used to go over to his parents for Sunday dinner. He continued to do this on his own for quite a few weeks without giving me an invite until I took matters into my own hands and told him it would be nice if I could go as well, unless there was a particular reason why he wanted to go on his own. He looked very surprised at my comment as he had thought that as I had not said anything, I did not want to go!
So don't assume anything where a man's mind is concerned! Honestly you men are so simple! Why can't you lot realise that us women need to have things spelt out for us once in a while!
So taking it that he is a typical man, I think you need to clarify what he intends doing, I expect he assumes that you will take the discussion as your invite, but I would definately ask him to make sure!
Best of luck! I am sure that everything will be fine!