Does holding a grudge count?

My students have been making medals in art over the past couple of weeks. When they were brainstorming what types of things they could choose, our art teacher asked them to think of something they've done in their life that they are very proud of. She also explained that it might be something they've done for a long time, like taking piano lessons or working on a puzzle that took a long time. Tanya raised her hand and asked, "Does holding a grudge count? I mean, I've been working on it for a long time now."

Granted, Tanya likes to think of a funny spin for most everything in the classroom, but this threw the teacher for a loop. She asked Tanya if that was something she could really be proud of, and I think that ended the discussion. But it did make me think about grudges. Why is it that girls in particular can hold a grudge so well? I've noticed during the last year and a half of marriage that Jonathan can always get in an argument, state his point, then drop it. Not me! I manage to hold on to my point or idea for DAYS! I realize that it's not something to be proud of, but I honestly can't help it sometimes. What is it in women that makes us so able to hold on to anger? And is there a way to get ride of it? It's not like I feel any better during the two or three days that I'm stewing over something stupid. Too bad there's not an anti-grudge drug out there...