Rapunzel truly is the best, most appreciative audience.. Inigo sure looks like he appreciates the attention right about now, bathing in it for a second or two until she asks that question.

Said question makes him look a bit more surprised. "Huh? Well, it's the only one.."

But he opens it up for her, showing the fact it's entirely blank.

"But I don't use it anyway, so I don't mind." Writing things down? Hah, that's for people far smarter than Inigo of all people!