I don't think it's a matter of allowing the coolant to cool off but more about allowing the heat to disapate from the stock air intake assembley. If there is no air flowing through the motor in between runs, the heat soak's in and stay's until the car has completely cooled down. I can gurantee that if you were to have touched the mass air meter before you started the car, it would have still been really warm. I say try the test again but allow the car to completely cool for a few hours in betweem runs.
let me set up the scenario for you. The intake is made of thin plastic and the engine is mostly aluminum. The car is sitting in a 49 degree sealed room with cold air blowing over it for 30 minutes (I had on a hoodie and leather jacket while working in there). Tell me how anything on it is still heat soaked after that. We actually had to run it for a few minutes to get the coolant back up to 170 degrees.