Lloyd,
The system should not use air except when applying the service brakes if I understood the explaination.
What Bruce is saying I think is that when his coach was sitting low it sheared off a fitting on the device that separates the toad air system from the coach air system.
What I do not understand is why Bruce heard air at times other than when he was applying brakes.
For your peace of mind you should do a pre trip inspection to verify everything is OK. After you hook up the Jeep, with the system completely aired up shut off the engine. Release the parking brake. The brakes should release, there should be a slight drop in the air pressure and then it should stop. The air pressure should hold where it is and there should be no sound of escaping air.
Then apply the service brakes and hold them. Again there will be a small drop in pressure as they are applied, but the drop should again stop almost immediately. Like before there should be no sound of air escaping. If you want to really be sure have Pam walk around the outside while you are doing this to listen carefully for the sound of air escaping. If she hears any you have a problem.
What Bruce said about not being able to raise the coach would strongly suggest the component in question was attached to the aux air circuit. Bruce, we need a more detailed description because the only air escaping should occur when the service brakes are applied.