Superhost Rating Issue

[Elliot4]

I noticed today that the % 5 star reviews listed in the Superhost qualification section of the Stats page declined for my listing from 79% (a day or two ago) to 77% (today). The issue is that the last 7 reviews I've had in a row have all been 5-star (according to the detailed rating breakdown further down the page, which I understand includes all reviews cumulatively and not just the last year as the Superhost section does).

How could my % of 5 star reviews possibly decrease when I haven't had any <5 star reviews between seeing 79% 5 star and 77% 5 star?