Marty,
Unless there is cracking or damage it is not so abnormal to have some low spots where water puddles a bit. I have several near the air conditioner up front. These roofs and framing are pretty robust, as RVs go, but they are not arched or formed well enough where no low points will exist, at least that has been my experience.
I do not think there are any simple repairs for low points. I would call that a blemish rather than a problem. If you find cracking or damage, that area should be reinforced and repaired with fiberglass. I pay particular attention to any sealant, gasket or otherwise, where I can see that water has puddled. Those areas tend to have more dirt settle on the surface after rainfall and drying so you can see where they are. The defect is if you get leaking and if so that need to be resolved quickly. Good sealant materials and preventative maintenance around mounted items on the roof are your best defense.
Later Ed