I wish the author would have expanded on that. I'm interested to know what the response was from the early customers. Did they accept? Did they offer to buy the next batch? Did they think it was weird and reject the offer?!
Out of all of them that I emailed, only maybe 25% replied - but those that did were very nice. There was no negative reactions at all.
I would like to know more too, but from my own experience with my clients they usually get very satisfied when you are as honest as you can be if you screw something up, and make it up for them as a gratitude token. People still value humility in doing business, they just don't want to feel "cheated" even if you it wasn't your fault really. I was really surprised at that, I thought I was done when I made my first serious mistake but my clients were pure understanding and support.