PR appears only when I click on the PR Bar

[geckoz]

Have you ever seen this and what does it mean?

[JayC]

I'm not sure that it really means anything directly related to the particular site. I've had some quirky stuff happen on PR gauge of the toolbar and usually it goes away eventually.

So I'd guess it means nothing about your site's PageRank. You might want to try uninstalling and reinstalling the toolbar, and see if it clears up.