Congrats on such a large & healthy litter! 7 yorkie puppies! Wow!
I don't know if it is common or not, but I can unerstand it since she had to be pretty cramped in there! I am so glad you took her straight on in like you did. I have decided that if I ever breed again (doubtful at this point) I will consider a trip to the vet as soon as possible after delivery to be essential for good care! So many little things can be happening in there and by the time it is obvious -- it can be too late.
Congrats again -- I can't stop grinning ear to ear at the prospect of all those little yorkie puppies running around very soon!