I live in a very humid area and am wondering if the climate may be affecting the factory applied covering.
Funny you should mention this. Yesterday I was training one of the fellows here with his Tower Trainer. The first flight went well... he landed, then it started raining. We got all our gear secures, but the planes all got a bit wet.
Once the rain cleared we put in another flight. Partway through the plane started reacting strangely and making a strange sound. I immediately took control and brought the plane in. The problem? One of the trim pieces on the LE of the right wing had partially let go, and was flipping up into the aistream and stalling the wing.
I've now gotten into the habit of sealing the LE of my wings with a single strip of ultracote or monokote that's wide enough to wrap around and cover about an inch on top and borrom. If the wing is a different color on top and bottom I use clear covering. Works great.