I loaded the stove this morning, just a few coals left. Emptied out some ashes, threw in newspaper, some very dry kindling and loaded splits on top. Closed the door, had the damper full open, the fan off and the bypass open. Usually takes a few minutes for the thermometer on top to pass the point where its hot enough for the catalyst to kick in and its ok to close the bypass. I was sitting just a few feet away doing some texting on my phone. I had looked up a few times and saw that the fire had started and was going pretty well, nothing unusual. Back to my texting. The last time I looked up, the top 1 ft. of the room was filling with smoke and the horizontal pipe (less than 3 ft.) was smoking black smoke. I immediately closed the bypass, shut the damper down and turned the fan on high. The class A tee was very hot to touch, I couldn’t keep my hand on it. I was opening windows and doors to get the smoke to move out. I went up to the closet where the class A passes (enclosed in framing and drywall) and could hear lots of ticking sounds. After a few minutes the smoke had cleared and the black pipe was again cool to touch. The class A was still quite hot, but improved. When I went to the window I saw black soot like pieces all over the snow. I cleaned the chimney a few weeks ago and found it clean. I did not clean the black pipe. Did I have a creosote fire?