Fiberglass pool discoloration....

[bhodges100]

I have a pool that was installed about 18 months ago. It's an ATHENS pool (40 X 16) and the color is called GALAXY BLUE. It is a saltwater pool and I have an auto cover on it. I also have a Pentair heater to keep the water warm in the fall/spring. I recently opened the cover after it had been closed for about a week. I noticed some discoloration along ALL the leading edges of the underwater portion of the pool structure (steps, ledges around the side, etc.) The discoloration is just a darker color of blue. It looks almost like they are 'water stains' or 'condensation' but they are all actually under the water line. There is also some discoloration along the sides and bottom and those seem to correspond with high spots if that makes sense.
I've had the company that installed the pool come out and look and it's concerning that they said they've never seen anything like it. They first thought that it might be water/moisture under the shell but they inspected the sump area and found no water standing (not sure of the correct term but it's a hole that is situated at the side of the pool that they use to see if water is standing around the shell). They have contacted the MFR but have not rec'd anything back from them yet.
Has anyone seen anything like this before?