"Common sense" of failures would suggest you're 100% correct. Without inspecting the failed unit, we simply don't know for sure. I've been running these 2 DECAs for well over an hour and they haven't changed. The coldest part of them is where the burnt coax is shown. I can't stop those that want to worry, from doing so, but I find absolutely no indication that the heat from a DECA was the cause of this failure.