Your post went from #24 to #79 in five minutes: http://hnrankings.info/6498675/

It happens all the time. I often comment on one of the top 5 articles, only to come back a few minutes later unable to find it on the front-page. I always thought it was a flagging issue, but considering the nature of your post, I'm starting to think it might be a bug with the HN algorithm.