Yeah, I get that... just that it's heating too fast IMHO- a couple of minutes for 40 deg change on a cool day with a slight breeze? Seems unlikely. It didn't feel warm, and if you've ever owned a black painted car you know it takes longer then that to warm up.
Honestly, I started having problems with the thermistors shortly there after as well... not sure what was going on, but all my analog readings became suspect after a while. Was too busy smoking the brisket and getting ready for the party to start debugging. Maybe I have a short or a bad ground... it's definitely a lot harder to keep all the wiring nice and clean one a perfboard then on a breadboard.
Hopefully I can figure it out and get things working properly- I've spent a lot of effort getting the thermistors to work and switching to thermocouples would not only be expensive, but end up costing a lot of time.