yeah.. I agree theres lots of heat going on there,maybe there is a short in something behind that, and is making the plastic hot.
maybe a wire is pulling to many amps.. due to a short or as thread said maybe just a faulty switch.. either way make them check/replace both the switch and the plastic cover.
I wonder if there is a wire for the optional stuff there.. I don't know which option is there I'd have to look in the manual.
it could be that wire is not taped and is a hot wire, if there is metal behind the plastic that would make sence Idk thou