It should probably be said that a new coach will always have some air in the lines that will work back to the tank after being used a few times. This is why most of us had to add some ATF at first. Once the air is gone your tank should stay full, otherwise you may be leaking which can be seen upon inspection pretty easy.
2015 Jayco Precept 35UN
Towing JEEP TJ with Roadmaster plates and bar w/Blue Ox Patriot brake
an Aluma low bed trailer with HD Road King and/or Polaris RZR onboard