With concrete, it's a good idea to install a vapor barrier before the concrete is poured. Not familiar with the use of recycled asphalt but i would think this could have been done as well. For now, i'd park the motorhome and see how everything works out. There's lots of air flow under there so i'm guessing this won't be an issue.
03 Itasca Sunova, Workhorse P32 with the 8.1 and 4L85-E