You mentioned in your SWH that you just can't wrap your brain around why she took it so personally. The thing is, you don't have to. Her feelings don't have to make sense to you in order to be her feelings.
My husband has a tendency to dismiss things if they don't make sense to him. It can be very, very frustrating. He doesn't have to understand why I don't like ham in order for it to be true. He can love ham all he wants, but I'm not eating it! He doesn't have to understand some of the things in life that frustrate me in order for it to be true.
My husband is an alcoholic (in recovery), and I don't in any way mean to use it against him, but sometimes it's the best example I can come up with. I can have a beer if I want to. I can have a glass of wine if I want to. I can stop at one (or two, if that's what I feel like). He can't, obviously. I have no idea why. Doesn't make any sense to me. Why can't he have just one? What's the big deal? I don't understand. The thing is, I never will. I don't know what it's like to live with addictions. But I do have to accept the fact that he can't have a drink, ever! He can't, because he can't have just one. So if he has one, he will want another one and another one and another one, and the fact that I don't know what that is like is completely irrelevant. My lack of understanding doesn't make it any less of a reality for him.
Let it go. Your comment upset her. Whether it should, whether it shouldn't doesn't matter. Just apologize and move on with your life.
For the record, I am a die hard Cubs fan, and my mom is a die hard Cardinals fan. We live in central Illinois, right in the heart of the Cub/Cardinal rivalry, which has been called one of the biggest rivals in baseball. We love our teams, but we couldn't care less about the trash talk. We don't do it. Never have. Never really cared. Not everyone who is passionate about sports does the trash talk. Doesn't mean they don't love their teams, they just show it differently than you do. Doesn't make it right or wrong, it just is. Let it go.