I've recently started using Arras as the theme for my site and it's caused a couple of Google News indexing errors - sometimes the Title of the article isnt indexed, but a random sentence is - meaning that the random sentence becomes the title in google news, which is obviously not good.
That's not really the problem here though (I read around and decided to un-hyperlink the titles of articles which should help)
But what is a bigger problem is that Google is randomly re-indexing articles at a later date, using the address of the article (eg. http://www.mysitename.com/archives/etc/article_title_here this is how Google indexes them first time) but adding on /comment-page-1 for the second time it indexes, so, http://www.mysitename.com/archives/etc/article_title_here/comment-page-1 is how it would be indexed second time.
The amount of time between this second indexing is pretty random, sometimes a few hours later, sometimes a few days...