Is it normal to see this all the time?

Ok well my girlfriend is allways doing somekind of hand signals .mostly when we are in the car and their is a Car coming toward US as soon as they are close, shes driving by the way, she brings her left hand towards her mouth as she is opening her mouth at the same time.but only when a vehicle is approaching and not too all vehicles.hand sign is in a circle using index and thumb.is it normal for me to be bothered by this?