diberry - 2:38 pm on Nov 2, 2012 (gmt 0)
But I set this up a couple of years ago. It's always possible Google is processing things differently now. Still, I would place my bets with those thinking Google is just re-crunching your site in light of these new links, and in the long run it'll all be good.
Another possibility is that a related posts plugin helps you as long as your readers use it, but hurts you if they don't. To the bot, it's all just links, but maybe if you had a bad bounce rate and now you've just given people even MORE links to ignore, that would look bad. But if people are using it, I think it should work for you.