Hi. Honestly, I don't think you have anything to worry about.
Not sure where you live, but I know allergy season this year is just awful, so it could just be from dust in her nose or something.
If you have any concerns though, it want hurt to stop it and go onto the next food.
Like you said, green beans are in the legume family. I have some info that I am going to post from the allergist that shows if you are allergic to (x) food than there is a % chance of being allergic to another in the same family.
I think peanuts and legumes are like a 10% chance or something.
Really though, I would not worry about it just for sneezing. If she is irritable, hives, swelling, notice in bowel movements, sleeping, etc. than I would worry than.
Hugs, Wendy