My baby is 5 months old and it seems as if she still has a peice of umbilical cord left in her belly on?

My baby is 5 months old and I have noticed for a while now, that she seems to still have a piece of her umbilical cord attached, inside of her belly on. I have tried to get it out with a q-tip, but it will not come out. Has anyone else experienced this? I don't know if I should just leave it alone and let it fall off when it's ready, or if I should bring it to the attention of my pediatrician. Any advice?