No, the top is cut as part of the natural production process.
A sheet of paper is printed with 400 images then cut into four of these along the dividing lines printed with the images:
Oops, I can't get my full pane of 100 image below 300 KB to up load.
Thus each pane of 100 has two sides with straight cuts affecting 19 of the 100 stamps.
Edit: Here is part of a pane showing the arrow and center line along which the panes are cut:
Cropped pane from Siegel's power search of which they have handled only one pane.