Dawgs, what I think is going on is that the smoker is trying to catch up to the temperature you set.
A Bradley is a relatively low powered device, even with a dual element mod. It puts out fewer watts than hair dryer. If your pastrami was large, and went directly from the fridge to the smoker, it will cool off you smoker dramatically. Under those conditions, it could take several hours to get your cabinet temp up to where you set your PID. The last time I smoked about 15 pounds of pork shoulder, the heavy load and low over night temps kept my dual element smoker below my 225F set point for 10 hours or more.
Another thought. Are you using a large drip pan with water in it? If so, the water is absorbing the heat. Until the water evaporates, your temp will stay reasonably close to 212F. If the only water is the smoker is in the puck bowl, that isn’t enough water to affect the temp much. But, a half size foil tray with an inch or two of water in it will really keep the temp down.
