Read the book "How to Win Friends & Influence People" by Dale Carnegie
http://www.amazon.com/How-Win-Friends-Influence-People/dp...
It talks about this a lot. Not always fighting to be right, or recognized, but still maintain respect and keeping good and positive relationships.
Sometimes, you just have to force yourself to let things go. You said it was no big deal, so treat it like it was no big deal. Give him the benefit of the doubt and respect him for who he is, not for a minor slip up.
When my husband and I argue, we sometimes need maybe 3-4 hours to calm down if it was a big fight (which isn't very often), so we can talk about it calmly. If it's a little spat, we usually get over it within a few minutes.
How do we do that? We go and do something fun together, we cook a dinner, watch a favorite movie, read a book together, change the subject and talk about other things, do something unselfish and nice for the other person, remember their good qualities. When we discuss serious issues, we speak respectfully, hear each other out, value the other's opinion, hold hands, and compromise until we reach a resolution. Unless it's over a serious issue, it's not worth anyone's time to have anger like this over every little thing and to hold grudges for so long. People deserve to be forgiven quickly and swiftly, and you deserve to not feel that anger.
Also, put it in hindsight, how would you feel if he was angry at you for so long over something so tiny?
Really, work on your communication skills, you don't want to go into marriage and parenting without the ability to do this. It will only get more difficult!