This is the end of my 4th season with my quad and am ready to put it away. This year when I gave it a vac and really scrubbed the heat exchangers I found this black sticky mess underneath the ash that was covering the tubes. The left hand side of the box has it also. I never have seen this before. I have burned all kinds of pellets (good and bad) and the oly thing I have done differently is burned 1/4 ton of old dominions at the end of this season. Could that be creasote??? If so why would it be there on the tubes and why from just this one pellet. I do have some creosote on my lint eater when I run it down the pipe a few time a season. Anyone else ever see this???