My niece was like that and it was fine...i think she was 8 when she lost her first. She is 10 now and now. She was actually born at 24 weeks and her teeth did come in a little late too. I had major issues because my adult teeth came in behind stubborn baby teeth and they didn't all move in and I needed major work done later. It was a pain.
Danielle, happy wife and Mommy to B, A and newbie J!