In this sentence:
I'm having some issue in understanding
そうでもない, and according to how I read it it reverse the meaning of the sentence: as far as I understand,
そうでもない means "not really", so the sentence would mean something like "Not very/really unexpectedly, Jinno Naoko nodded", but I'm not sure about
そうでもない and I can't find it on my grammars.