That's exactly why it stood out to me. They often changed the slant of their writing or adjusted the style a little, but it was still technically in print. One person's writing didn't change at all between his regular handwriting and his signature.
My signature is more of a scribble. ^^; All that people can probably make out are my initials (KH on anything official; TH on anything I'm not required to use my legal name on).