Excuses at 5 years old?

It was a crazy week, filled with unusual behaviors, never before seen by me, and new statements from my five year old that I wasn't expecting to hear until he became a teenager. Today he came to me and said, "Mommy, I for sure have a fever and I can't go to school tomorrow." I did one of those double takes and said, "What?" He said my head doesn't feel so good and I can't go to school. Where do they come up with this stuff anyways.