Hmm. I wonder if this has anything to do with why the Sunday April 4 episode of The Simpsons was about libraries. I missed a bit of the beginning, but it seems the local library's shelves were empty due to funding cuts, so Marge entertained the kids by telling them historical stories. Then we saw the stories acted out, with Homer as Henry VIII, etc.

I think there have been times in the past when a lot of cartoonists agreed to work a certain theme into their strips on a certain date.