I would take the control center reading with a grain of salt. I have never found that monitor to be overly accurate, on our Georgetown or in past coaches. Go outside and look at the gauge on the tank itself -that will be much more accurate.
As for being "topped off with a mix of propane and air" - I'm not sure how that could even happen? How would one do this?
I think the more likely explanation is an inaccurate reading at the control panel.
BTW, sort of related to this - we noticed our propane level dropping quite quickly over the holidays and discovered the regulator vent was leaking. Had to have the regulator replace at the dealer and now all is well.
Mike & Suz
2014 Georgetown 351
Pontiac Vibe toad
Buck & Patsy, the boston-mix guard dogs