Old leaking EPDM rubber roof, it seems in the rv world that caulking is a roofing product. We don't share the same admiration for caulking. The poor roof design of most recreational vehicles makes them prone to moisture problems due to poor or a total lack of ventilation.
Moisture is not uncommon to any RV owners on the south coast, retail & RV stores sell a number of band aid solutions including fancy vent covers that they claim will stop leaks. It's a given that some leaks will be stopped when you install a vent over a vent. However none of these products are installed with the use of the roofing membrane and are prone to failure.