I began a smoke tonight and as the Temp gage passed through about 190, everything looked fine. Smoke streamed out the vent and there was a little door leakage. ALL OF A SUDDEN, it was like the smoker burped (analogous to a flash fire). Heavy smoke shot out through the door cracks and jetted through the top vent in a 1 second burst. Gages and smoker showed normal but I have never seen nor heard of this. The vent was free of obstruction.
Before putting in my boneless pork butts, I did tie them up in cotton string and for the first time, I used a spray of Kirkland canola oil cooking spray on the grates for easy cleaning. That is the only thing that was different from previous smokes.
Any idea what may have happened?