@shadowgrail While Nagatoro being worried over not knowing Senpai like she thought she did is sort of implied. Her nervousness is more based on both her wanting to win the bet (due to her competitive nature) and mostly her wanting to make sure Senpai is not a herbivore.
Nagatoro has shown attraction to Senpai multiple times, more evident when the way she acts around Senpai is compared to how she acts around other guys. Put yourself in her shoes; if someone you like was showing signs that he/she was not into dating, period, wouldn't you be somewhat nervous at the prospect of your crush never being interested in you.
Plus, she never says anything along the lines of "Trust me. I know Senpai very well." Also, when Nagatoro finds the ero-manga, she doesn't say "I knew you were a pervert all along, Senpai." She just proclaims that Senpai is a gross pervert repeatedly with a nervous grin on her face. Possibly Nagatoro masking her relief that Senpai is not a herbivore.
You're more than free to your interpretation of the chapter, I just wanted to explain my interpretation.
@Variousletters Took the words right out of my mouth.