Nah, she always knew Xykon was dead. He's just not dead enough for her comfort.
Well, It's not really my find. The commentary (I think?) of the last book stated that this one would feature an important ally who had only appeared for one panel so far. People started guessing that was Sunny as soon as they were visible. My own guess was it would be this bugbear, who had already shown up somewhat prominently in a wide shot.