Dave, we had a similar great experience. All the literature we looked at said the optional sofa bed we ordered would have an air mattress which we believed would be much better than your ordinary hide a bed mattress.
Well, when we received the coach it did not have the air mattress

As in your case, the next model year didn't come with the air mattress, our coach was built in February when they were gearing up for the 2009 model year.
Our salesman (great guy, now retired) worked with Dave Garl (Newmar rep) and another dealer (Howard RV, another great dealer to work with) and installed the replacement with the air mattress, all at no charge
Newmar could have hidden behind the 'specifications can change at any time' legalese in their brochures but they didn't. As we expected, the air mattress is much more comfortable. We couldn't be happier
Stewart