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The link above is where Tobi states that he is not sweating and that it is rain. Second afterwards he is questioning himself these are all characteristics of being nervous, but it is indeed left up to interpretation. BUT bottom line is he was not sweating but he thought he was, when your mind plays tricks on you with bodily functions it means your nervous/distracted. Either way we won't know if he was nervous or not unless Kishi says so. BUT we do KNOW that he was not sweating.