DD does this also - she goes through phases of being into smells - she will smell paper and other things including her hands - I usually just ignore it.
It might just be a nice feeling to tickle under her nose. i wouldn't worry about it if it is isolation or if you think it's affecting her socially. I rub my thumbs when I'm bored/stressed etc which my DH picked up on but I had never noticed, just a comforting feeling
I would be getting into contact with her teacher, if she doesn't notice she's doing it, it's probably an unconcious urge that her body follows through with.
It could be a mild case of OCD, probably not, but it's worth getting it checked out.
I grew up with all sorts of habits like that, so did my brother and sister, and now I see it in a friends daughter and my SIL (who is 11 and not blood related, so not running in family). It can be a type of anxiety, or control. It won't lead to OCD so don't worry (well it may occassionally but not in any of the above mentioned). I am no expert but I would say it's a habit. My mum used to give me three weeks (time it takes to break a habit) and then I'd get a reward. Maybe try that with her.
xo
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