What does it mean that this guy got mad at me for opening the door for myself?

He's an old fashioned and polite boy and you are a liberated girl. But it would have been nice of you, to allow him to open the door for you, it's just good manners. I don't think he should have got mad at you, but should have just let you know, he wanted to do it for you. A person with manners, does that for anyone, male or female. Sadly manners are sorely lacking these days.