I have a weird occurrence when recircurlating my mash. I don't start the recirculation until after 15 min or so. During that time the temp stays solidly at 150. When I start the recircualtion after about 10 minutes the temp, on the kettle gauge, jumps to ~168 and comes back down after about 15 minutes to low 150s. Any thoughts? I know the temp of the 40 lbs of h2o, 16 lbs grain, and 15 lbs of kettle wouldn't be able to jump 20 degrees instantly. After all I am on earth and are bound by the physics of earth so waddup?