Baby born with sacral dimple

My baby was born with a sacral dimple is still in the crack area so not on the back but I noticed it has a path of hair on each side of the dimple and now I’m getting worried of course because I google everything. They gave her an ultrasound when she was born and they said it looks closed and that it should be fine but that’s not promising to me. Anybody have any experience or their little ones have this? I’m just wondering how old they have to be to realize if there’s a problem or not. She’ll be 8 months old tomorrow.