On cleaning my HS20 tonight I noticed what appeared as dust laying on the inner lens. On closer inspection it looks like maybe condensation. However, after about 3/4 hours of use it remains there so I guess it's not that. I've attached a thumbnail, if anyone has any idea what it is and more importantly how to get in there to clean it. It doesn't affect the picture in anyway, but I would like to keep it clean for my own sake.