I am running Vista Ultimate (SP1) on a self-built PC. I am using the newest version of CCleaner, but I first noticed this happening a couple of versions ago, sorry I can't be more specific. My browser is Firefox 3, and I always close everything before cleaning. I only use IE7 for Windows Updates.
This doesn't occur every time, just occasionally. I run the cleaner usually after I close my browser. The last time I ran it (this morning), analysis showed 27.72 KB, and the cleaner was the same. I have FF set to delete temp files, cookies, etc. when I close the browser. I'm not having problems of any kind, someone just addressed it on our forum, and several others chimed in and said they had noticed the same thing.
If this is not enough info, let me know.