lucy24 - 2:57 am on Feb 4, 2012 (gmt 0)
Oh, that reminded me. Preview request #3, using a third browser and different search string-- ###! If I'd thought of it I would have tried from the library which has a different IP and, of course, entirely different computers. Must still be cached, because there's nothing new in logs.
I did find an unrelated adding-insult-to-injury entry though. In fact, two of them back to back. Two different people inexplicably asked for Previews of a page that included hotlinks. Grr. Nothing to do about it except what I'm already doing, which is to show the garish No Hotlinks image. The offending site comes through as referer, with Google's IP, and Preview in the UA.
What I don't get is that sometimes the Preview is quite stale perhaps days or more old with a much newer version of the same page viewable in the normal Google cache, while other times the Preview is very new but the cache copy is days or more old.
I think that reinforces the idea that the Googlebot and the I Am Not A Robot don't talk to each other.