Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
This is not normal and if your sweet girl has had puppies in the past, this could be scar tissue or the beginnings of a Mastitis which is an infection. I would urge you to haveyour vet examine your sweet girl to know for sure. If there is a developing Mastitis, she will nto be able to nurse the puppies using these teats and you need to know thsi for sure. If this is scar tissue from a previous litter, then it is no problem for your sweet girl. Better to know now.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
Sincerely, ***** *****