J.R.
Constantly, constantly, constantly gently remind her when you catch her in the act and help her choose a different, self-soothing, more socially acceptable little habit. Choose a few different options. And teach that she must go and get a kleenex whenever she needs or wants to touch her nose. The act of doing that might be enough to re-route the habit.
After you rule out allergies, which you should check into, and if she does not make the transition to another chosen habit, this is to disrupt the behavior, then your motherly hunch is probably accurate, she might just have a tick. Most children will indeed outgrow them. You don't mention her age, but if she has not out grown the habit by 9-10, you might consider an evaluation by a pediatric neurologist. And most important here, make sure you video or record the ' tick' behavior as many times as possible so that a healthcare professional can observe it in case she doesn't do it in the clinic. The newness of a clinical setting is enough for any youngster to switch their focus.
Happy parenting!