Brian,

The door to the pre-heater should be fully closed above 60 degrees F. I'm not sure exactly how quickly it should close. Probably pretty slowly. If it doesn't and stays open drawing hot manifold heated air when ambient temps are high ... it's widely thought you'll eventually fry your Air Mass Meter. Yours seems to be closing but I'd check it again when warm weather returns. The thermostat in the air box that controls it is easy to replace and about 15 bucks. Much cheaper than a $200-$300 AMM. Some brick owners just block off the pre-heater inlet rather than chance a problem. I replace the T-stats when they go bad. That after having one stay open and yes I did have an AMM failure. Like I said in cold weather it shouldn't be a problem and yours still seems to be working.But keep an eye on it.