Steve,
I can't speak to the possibility of an air bag failure based on your discription. It should be fairly easy to go thru the sequence of airing up the coach to 120 psi and see if everything is level and normal with no air hissing noises anywhere. Next, go thru your leveling sequence as you normally would do. Next go thru your air dump sequence Note: make sure front wheels are facing straight ahead.
When you go to depart and push the travel button, you activate the "6 pack" solenoids located in the front & rear and change the solenoids from the "leveling position" to the "normal ride height". You may have a leak at either 6 pack solenoids. See photo. Hope this helps, Fred