While I think there is some merit in what everyone is saying I have always been curious about the process in which certain things happen. It may not always be possible to assign a cause to things but by process of elimination we can reduce the possibilities of certain things happening.
The cut in your note is rather unique because it progresses through three layers of films. The fact is that it is difficult to initiate a cut in a polymer note because the two layers provide different resistance in different directions. So try ripping the note with hands and it will not do so despite your valiant efforts.
Once the cut it made however it weakens certain portions of the films and the cut can progress in certain directions therefore easily tearing the note. So if you have a tear then it is easy to rip the note along the tear. There are certain inherent flaws that are related to production that will create such types of tears. For instance I have seen that a strong strike to the tactile dots results in a situation that will initiate a tear from the dot.
What is unique about your tear is that is goes through the polymer film. If the tear had started at one of the edges it would have difficult time progressing through the polymer film as it would provide some resistance.
Unless of course the shearing happened through the guillotine type of action or a cut was initiated with a scissor like device from the beginning till the end. In short the cut had to be made in one go and not progressive such as in ripping apart a small tear that had initiated.
Here is an offer for you. In the area that is cut, if you can see two plies of the polymer when looking at the face - as opposed to the edge) that are offset (one is a bit whitish without any printing) then I am willing to pay you $21 for the torn note and $20 for the other two consecutive notes if we can meet somewhere in Toronto to affect that transaction. (I would need all three notes)
Cheers