@Esther13:
All hosts who have been doing this a while receive what we feel are unjustified reviews. Recently we had a guest walk into our home and said, "Another crappy mistake on my part" and gave an according review. Meanwhile, same house with nothing changed, a different group arrived and it's "OMG!!!" and a great review. Just a like everything in life, everyone sees things a little different.
How we respond to those reviews is even more important. In your case, this guest did nothing to hurt your business as your average star rating remains very high. Quite frankly, no one would even have known the guest left less than five stars if you had not said it in your response. As a potential guest, I would have thought nothing of his review, yet, unfortunately, your written public response would turn me away.
I think there are lessons for all of us here. First, we are not robots who think alike and, second, sometimes we just need to sit back and take a deep breathe before responding.
Good luck in your homes. About three more reviews and this one will be on page two and forgotten.