I upset my roommate
How many times have you done this?
A few times.
Well, the best thing you can do now is apologize to them. Do it soon so this doesn't linger over your heads a second longer than necessary.
Nah. I'm just going to move on and pretend it never happened.
It's not a good idea to leave this slight unaddressed as an apology would be the right thing to do. Set aside your pride and indifference and say you are sorry so that you don't strain the relationship.