ask her if she wants to be more comfortable with it.
people generally do not look at the faces of others when they are in crowds or walking by eachother in the hallway or in similar situations. It is considered polite to quickly glance up and the quickly look away unless the parties know each other.
So, if she is comfortable and others are not complaining about it, then it is probably within normal conventions. If she is not comfortable, or others make note of it, ("why wouldn't you look at me in the hall? are you mad?") then it is not normal.
