The same happened to me. I am also a frequent Airbnb traveler as well. I feel strongly that this is not acceptable and that the algorithm should alert the reviewer of the incoherence between an overall 4 star rating and five star ratings in each of the six categories. Keep in mind that if you click less than five star in any category, the algorithm asks you follow-up questions. This doesn't happen for the first overall rating because the six sub categories are expected to provide clarification. The other potential solution is to elimintae the overall rating and simply average the six categories. The current situation is totally illogical and undermines the credibility of the whole system. Finally, it is more than likely that it is a typo error or lack of attention by the reviewer that caused this incoherence, this is why it is imperative that the software should not allow this scenario to happen and force the reviewer to clarify.