Re: upset with the professor
There is no use insisting to a professor once he says the grades are alright. If he had realized his mistake the first time you mentioned to him, he would have corrected it. By insisting we create trouble for ourselves.
If you get a chance, apologize to him for insisting too much, and tell him that next time you would try to perform better. It is better to have good relation and impression on a professor whom you would encounter in future as well.