Greetings: To answer your question, yes, the white line in the heart is the opening of a pen nib (a heart and a pen combine to write words of love). In the original, there is a subtle shape of the rest of the pen nib on the surface of the heart -- in the attached revisions, I have strengthened this shape somewhat to make the shape more apparant.

(This comment references Entry #31)

Thanks for the clarification - very cool idea. I'll be re-ranking later on today.