It almost appears as if something heavy was placed on top of the H. Perhaps in a case where someone tried to use it as a chair. I can see that happening even if the owner isn't aware it occurred.It's very strange, I'm just trying to understand, you did refer to it as the top shelf, which suggests you have familiarity with self builds, and maybe curiosity or reason to open it up, I'm not point fingers, just asking questions as it is a bizarre and unique issue among users here.
Can you let us know what the Yuneec determine the cause to be, maybe it's a bad mould whatever it's a mystery to be solved!