I haven't used Future for coating of clear parts. I was always afraid of unpredictable reactions between the adhesive of the protective tape, and the layer of Future. Sometimes the interval between the installation of the tape and its final removal is 2-3 weeks.
It really looks like some kind of moisture, which I tried to remove by exposing the model to direct sunlight, by carefully heating it with a hair dryer, but nothing happened. That strange moisture remains in place and unchanged even after a few months.
I paint most of the glass parts before gluing, since I often paint the inner frames as well. When the paint dries, I remove the inner protection tape and glue the transparent parts for the fuselages. The outer protection is generally well sealed with additional Tamiya tapes and liquid mask (Mr.Masking sol NEO), as in your picture.
The problem occurs in both summer and winter, so humidity is not crucial. I never wash transparent parts before use, nor do I touch them without gloves.