I know that is old news to most but I had several old blogs that had used markov and caffeinated content back in 08-09 so all the old posts were buried deep in my blog. I had moved on to other content providers and just left them. About 2 weeks ago I noticed one of my old blogs got deindexed then another and then another. It looks like from the spider acitvity on my site they went through those blogs and because of the old markov and/or caffeinated content they deindexed them. You may want to remove any old posts made with either.