Dennis, I'm burning oak that is 1 yr seasoned and shows 19% and 2yr maple showing about the same, and there is always more soot on the left corner of the glass than any other location. Would this indicate an air leak? If so, how would you resolve it? Stove chalk the inside joint in that area? Might call woodstock and discuss this......thanks.
Take a lighter around the outside of that glass and see if the flame gets sucked in anywhere. It could be a gasket issue or maybe just draft or weather conditions.