I dunno, This happened on my last bottle of IW. The older it got the more liquid it got? perhaps I didn't shake it up enough in the times I used it before and was left with a lot of oils? I dunno. I could definitely see some residue, only by my garage motion light (100w halogen) and after waxing and before waxing the first time you could see the dust accumulate in the patterns i wiped it off in. (woo bad sentence structure)