To the original poster. By all means DO check for leaks as noted above by others.
Now: I have had it happen (ONCE) much like you. I smelled propane in the area of the tank fill.
In my last post I complained about mis-information about a valve.. Well what happned is the tech was a bit slow closing it and the area around it got contaminated with odorant (propane is oderless they add odor to it for your safety) Eventually it evaporated and vanished and there was never any leak.
Another POSSIBLE causem I have not seen this on Motor homes but I have on portable tanks.. On portables there really is an Over pressure Relief valve
A tank filled on a cool morning to 80%.. Well by the time it sat in the hot afternoon sun for a few hours. that valve was venting propane.