I live on a well and each morning I get a small blast of air when hot water faucet is turned on (only in my hot water line) and this has started only in the last week (26 NOV). Some background information. I filled a glass with cold water and let stand overnight. In the morning there were some bubbles along the side of the glass. Middle of Oct, I had repairs done in the backyard which required a bobcat hauling dirt to go over my well line. The construction people told me that the weight of the tracked bobcat carrying dirt was not enough to damage the pipes - I live in State of Maryland. I also drained the hot water heater in the beginning of NOV as water temp seemed lower - since then, the water has been hotter. I did not adjust the thermostat - 116 degrees. My hot water heater sits on several bricks which are in contact with the concrete. I have not tried to shut off the well pump and let system stand for the day - hard to do with everyone home. I have not noticed any drop in pressure after a couple of hours. The air discharge is a single burst and all good for rest of the day - so far. Also have a water softener and added salt 3 days before occurrence.
Thank you for any assistance