I thought it was moreso that it clicked with her why she was really making such an effort on her appearance when Nitou didn't show. idk though, I think a thorough rereading of the entire thing is in order. :D
Yup I think thats it also, it explains the second "Oh".
Ever since you mentioned this I've been very curious if this is really true?
I wouldn't know exactly how common it is but I do the hair toss sometimes and I know some other women who do it to. For me it's just a subconcious thing. Tossing your hair, touching your hair, slicking back your hair, running your hand through your hair it is all just an easy form of preening and men do it too. It's a lot like how some birds act. Don't even have to have an intended target in mind.
Though a lot of times a hair toss is just a hair toss. Oh I also used to have a friend who would toss her hair when she was angry too, so yeah best not to overthink it.