You can clearly see where he wasn't able to edit the image properly. the top of the sign and the bottom right corner are off and show the edges of the original sign underneath. that wuld not be there in a photo of someone holding a piece of paper.
What I see clearly is the black binding along the right indicating that this is a notebook, not a single sheet of paper.
EDIT: OK, I guess it is a shadow, not black binding. But it is still clearly a notebook. Not really sure why you care to begin with.