Just a thought, but you may want to try adding some type of heat sink (sp?) like a foil-covered brick or paver the next time you smoke a single loin.
I am not sure that this would have caused it, but smoking one tiny 3lb loin in a 2D could result in the temperatures going all over the place. Smoking such a small piece of meat is essentially like running your smoker empty which we all know does some wild things.
I agree with the others that your description does not make sense. So, just throwing out a possible cause.