That's Not Funny!

I was driving to work this morning and heard a story on NPR about the Notre Dame vs. Alabama game tonight. It talked about the match-ups, and the history of both schools, and the cultural subtext, etc. But then the commentator mentioned that Alabama fans were upset about a t-shirt - saying it was stereotypical and hurtful and all that.

It was the first laugh of my day. Then later in the day, I saw this cartoon (xkcd.com):

Should I be offended? Because I'm not. I actually thought it was funny. I am going to assume it was meant as humor. But the people who are made over the t-shirt seemed to think it was a hand-wringing offense to their humanity. Am I wrong here?