I walked past my stove pipe the other day, and noticed that there were 2 strips of white "drippings" coming down the pipe. There is a black dripping too, which is sticky. The white was sort of chaulky. We haven't burned anything in the stove for a few months, and it was last cleaned in February. I haven't pulled the pipe off to see if anything was in there, but it just seems like an odd place to get dripping. This single wall goes into the ceiling support box, then directly to the double wall pipe and up 6'.