Where’s the crease?

Dialogue from the movie Catch Me If You Can:

You should fold it.

What?

That note. It’s a fake, right? You should fold it.

It’s… It’s a note from my mom—I have a doctor’s appointment.

Yeah, but there’s no crease in the paper. When your mom hands you a note to miss school the first thing you do is, you fold it and you put it in your pocket. I mean, if it’s real, where’s the crease?

If the devil is in the details, consider me the devil’s advocate.