Might be a sign, so far this year 2 birds have gone down the pipe and into the stove. I've had this stove a long time and suddenly I have birds1 Just a tip for anyone that has this happen. We used a clear plastic garbage bag around the front of the stove. Reached the handle and opened the doors and the bird flew in the bag so I could take it out and release it. I do have a cap on the insulated chimney, it's a band style.