Probably is a bit. I'd never heard of this tradition (if in fact it is one

) until the movie came out. But afterward someone seems to always offer a coin, or someone else says to offer one.
Frankly I find it a bit annoying as it makes no sense. Why if you want to end a friendship would you give someone a piece of cutlery? That doesn't seem wise, for a start. But also why give such a good gift to end a friendship? Seems to me if you want to end a friendship a more effective gift would be a flaming bag of dog poo or pictures of you shagging their wife.
And then the coin. Well in the movie, if I recall, they put it as a native American tradition, which makes no sense as there were no coins in America before Columbus. But also there is the notion that if given a gift that was to end a friendship the simple act of giving a coin, and one that never seems to be reasonable to the value of the knife anyway, now somehow magically changes the persons mind. That's not even taking into account the idea that now the other person is really buying a knife from you, on the cheap, but from the other persons perspective that they need to buy friends, an insult in itself.
"Here's a sharp object, go away you annoy me!"
"Wait! Here's a dime, will you be my friend?"
The whole exchange is riddled with insults. This is one bit of knife lore I could do without.