So, I've had a 5 pound flat on the smoker for 5 hours ( temps. between 220-240 ), and at the 5 hour mark, had hit 141 internal. However, in the next 30 minutes, the temp. dropped to 138 internal. Anyone ever have this happen ? It's a really strange thing. I usually do briskets larger than this, and dont recall ever having it happen before. Any thoughts ?