I doubt they would strike one coin, then change the die because of a chip. So in my opinion, if it is a legitimate mint error, there should be several examples in circulation.
I'm not even sure how they would fix a mark like that in the die. trying to polish it out would leave massive artifacts.
Do they ever repair a spot like that with weld of some form and then polish out the spot. If so they must have struck many before pulling the die.