no, not at all - my daughter's second tooth has just come out and she's just 5. her first one started to wobble about six months ago and took AGES to come out.
She got a teeny, tiny letter from the tooth fairy too. I used to get tuppence!
My son was only 4 when he lost his first teeth. He had all his second teeth really early and as an adult he has the strongest set of teeth imaginable and has never had to have any dental work!