School and What-not

I finally got my grade from the first class in pursuit of a Masters Degree in Education. I did very well. I'm not sure how my final paper affected my grade, but I did find a flaw in the thing. I used a rather generic quote from a website in the paper. While I did site the web page in the document itself, I forgot to list the site in the references. I should receive the paper / portfolio in the mail any day now and will be able to pick through it for errors. So what grade did I get in the class you ask? "A-". I've never been a stickler for grades. If I get a "B" or something close to it, I'm happy. So why does the "-" in front of the "A" bother me so much, when before I didn't have a care in the world? Maybe it was the mate's comment "You only got an A-?"! That big, brained smarty-pants bastard! He has to ruin everything!