No idea if it can be updated, but this has happened to me a number of times. I get 'sparklingly clean house' and 'amazing host' and so on, with 5 stars all the way through, then an overall 4-star.
One person I queried this with told me she has never given 5 stars to anyone in their overall review.
Another one told me that she had seen a spider in one room so marked me down for that although they had a great time (she was staying in a 150-year old weatherboard farm cottage!).
I've stopped asking now, as Airbnb never came back to me on any of my queries about things like that.