[1] http://news.ycombinator.com/item?id=1782058 [2] http://news.ycombinator.com/item?id=3894695
So maybe it was just a case of HNers flagging the story as it became popular, as the title was fairly link-baity? I was under the impression that flagging a story kills it rather than suppresses it, but regardless, if that's the case then it makes sense.
Edit: One comment in your example link by ColinWright seems to state 2 or more "flags" can cause this behaviour: http://news.ycombinator.com/item?id=3893207
If that's the case, it's probably best people don't know about it, as used maliciously it would be fairly disruptive.
You can't know -- just because it wasn't in your office doesn't mean it didn't happen.
One of the first readers to see it may have mass emailed his/her colleagues who all read/upvoted when they got into work in the morning, for example....