Hi Schlink, welcome to TradGang!
As a lefty, I assume you cant in a counterclockwise direction? That could turn a nock high into a nock left, depending on how much you cant.
Also, as a lefty, my understanding is that a true nock left indicates that the bare shaft is too stiff.
First, it may mean nothing, if your nock left is really a disguised nock high.
Second, it could mean that when you cant, you don't draw as far back and therefore arrows that were in tune when you held the bow vertically are now stiff. I was bareshafting some arrows this morning, and it was amazing to me how little difference it took in my draw to turn weak arrows into tuned arrows into stiff arrows.
If you are that close, I would call it good for now. If you develop more consistency as time goes on, you can always try again. That's why I always carry a bare shaft in my quiver.