I just installed a slightly used Harmon XXV anniversary pellet stove. When I get it going there is a very slight smoke coming from the pipes. It doesn't really smell and it is often hard to see, ususally I need a flash light to see it. I have only started it a few times and let it run for an hour so and then shut it down. I have a very thick layer of high temp silicone sealant on the pipe seems, could it be that curing? Any other thoughts of what it could be, how to fix it, or if it is nothing to worry about? Thanks so much for your help.