Last time I checked the PR of one of my sites was last week and it was PR 1. Today is my weekly SERP checking etc. and I was surprised to see that one of my sites dropped from PR 1 to PR N/A! Has there been a PR update from Google today? I used ScrapeBox and about 22 other PR checkers online and they all say that my site is now PR N/A. I didn't change one thing on my site. What the hell? How is this possible?