once the flame show in the stove is over and there are no secondaries left, i seem to just let my coals burn down at whatever air setting i had it at (normally about 1/3-1/2 open). my question is if i shut the air to as low as it goes (10%?), can that lead to creosote buildup, or by this time of the burn stage, is there effectively no creosote-causing vapors left? it's just a pile of red hot coals...