i also noticed that and my guess is that's just the way how their algorythm works. It recalculates the current pr on the fly, that is when you go to your page from higher pr referrer such as 5-6 then your pr might be read as 3, when your referrer is 0, then the referred to page may change its pr from 3 down to 0, as well. Google's internal wheels behind the scenes. Pr is not cast in pigiron, it's just the relative measure of relations between referrer and referred to. Therefore, pr per se is worthless, it's good only as a measure of good/bad linking, that's all. At least that's what i think imho
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