Very interesting, From the proportion of your hand and the width of the cuts you must be using a 2 inch wide engraver! :just kidding:
I would have to disagree with your statement, "I wasn't thinking of the golden ratio when I drew the letter so the results are strictly coincidental." Your gray matter has been programed to make the "pleasing proportions are a result of being close to this mystical ratio," your designing software perceives what is "pleasing" so the drawing is not "coincidental." You are in tune with the "mystical ratio," in my humble opinion on your humble statement. This process is what is the "art" in engraving.
I agree with Sam on this: these "pleasing proportions" are so pleasing, they can be found everywhere in nature.
In my lessons, teaching on the Greek 'and earlier' art, I ask some of my students to draw an egg 'the way it really looks', others I give an egg. I ask both groups to measure and divide height by width. Count all the outcomes together, devide by the number of outcomes and you arrive for both groups very close to the golden means.
It's not 'scientific', but it demonstrates that nature and what we make of it in our drawings and art, are both very pleased by these proportions.
Jeroen
Btw: I use eggs as they are easy to transport and measure, keep their forms and are known by everybody.