Where did my comments go?

I was googling to see if I’d already posted some stuff on LessWrong, and I found it in a web cache, but not on the site. Compare Google’s Sept. 8 2010 cache of a LessWrong post to the version now on LessWrong. Everything between the comment made by MBlume on 20 April 2009 02:58:50AM, and the comment made by Alicorn on 19 April 2009 10:11:55PM, is now missing, including all 5 of my top-level comments, and some top-level comments by JulianMorrison.

I didn’t delete them. Does anyone know what happened to them? Is this happening to other comments?