Title says it all. while operating the stove, I hear "tings" or what sounds like something hitting the inside of the stove. It's not very loud and seems to settle out once the stove is up to temp and cruising and towards the end of the burn. Is this just the sound of the metal parts expanding from the heat? Is this normal or an indication that I'm going from cold to too hot too fast? Or is it just particulates bouncing off the inside of the stove and liner?