I wouldn't think so. Single babies are not rare, and yours was sadly premature, so the chances of a big one stuck in her are pretty nil, especially after all that time.
Can you gently feel mummy's sides? If she is flat in the back, then she hasn't got any more babies. Please take good care of mummy. The loss of a baby is no less devastating on a piggy mum than a human mum. Spoil her with good food, plenty of vitamin C and hay and keep her warm and cosy. Because of the long pregnancy, problems with pregnancy and birth are MUCH more frequent than in other rodents.
If mummy isn't looking right, you need to have her seen by a vet as soon as you can.