It seems like there are several threads around the SEO forum space that have discussion on a recent PageRank update. Yes, even more recent then the June PageRank update.
In the Google Webmaster Help, Googler, JohnMu, replied to one webmaster saying that he/she should not worry about the last PageRank change because it was likely a "technical quirk."
The way John said it, made it sound like the error was on Google's side. Here is what John said:
You have a nice-looking site :). As far as I can tell, it looks like the change in Toolbar PageRank for your site is only due to some technical quirk and not something that you need to worry about.
So I am wondering if the recent PageRank update noticed by a small percentage of webmasters, was a technical bug on Google's front?