That means you're doing something right. I don't know if you're giving her chews, brushing her teeth, giving her mouthwash or whatever.. But keep doing it!
Taking care of their teeth is very important as bad dental hygiene can lead to all kinds of health problems (just like humans) and can be painful and expensive to fix. Their teeth are supposed to be white (contrary to popular belief!) and if they're overly yellow or brown, should be looked at by a vet.