Congrats on the newborns. Birthing is such a special time.
Some newborns might still have some yolk sack attached. I would not say it is normal.
Having a large amount would concern me. In those snake I've usually seen physical developmental issues. Usually an open G.I. tract.
If they look normal and the umbilical cord area looks normal I wouldn't worry about it.
Were they able to break out of the egg sack?