We did add the plugin and we are monitoring it. Last night, for example, the plugin generated a lot of updated CSS files and a handful of of the more transient CSS cache files. And it’s on pages that no one touched. It was, after all, the middle of the night. Anyhow, we’ll keep an eye on that.
I think what I’ll do next is add in logging on the CSS delete calls. I already hacked it to not delete, so I might as well try logging those calls from that same location.
Perhaps a log of the calls to delete CSS cache will help track down the cause.