They are installed about 10 inches above my sheet metal roof. The solar panels are Monocrystallin.
It isn't normal in the sense that it's normal operating procedure. It can be normal in the sense that it does happen as it is hard to keep moisture out over the long term.
That is the answer to your specific question and I wonder if you more want to know if you should or need to do something about it or can stop worrying about it.
You do need to do something about it. My understanding is that moisture degrades performance, can cause electrical issues or corrosion, and can shorten the overall lifespan of the panel. Moving forward, I suggest contacting either your installer or the manufacturer to discuss the situation and what to do about it, and who pays for it. Also I suggest reviewing your installation contract about warranty and service.
No, visible moisture is not normal. PV- panels are sealed and air-tight. But the sealing can suffer from mechanical stress during transport, from wrong handling, from mounting or operation. Every bending, twisting etc. should be avoided. Sometimes the building roof is under stress by setting effects, traffic, earth movings, heat etc. which impacts the panels.