if all the puppies had them on all four paws I'd probably raise a brow, but otherwise as stated above... yes, white toes as well as chest patches are not uncommon in PB and typically become less prominent as they age. sometimes fading completely.
Every GSD puppy I've had came with some white on their paws and usually a little dot of white on their chest... almost as if they were not quite "finished yet" but oh well - time to get born These always went away by the time they were 4-6 mos old.
I imagine this would be hard to explain to potential adopters... there must be some documentation somewhere online that discusses this and it's not to worry.
My puppy is 11 weeks, and he has white toes, at only 11 weeks, they're starting to fade slowly, the breeder is a champion breeder and has been breeding for over 30 yrs.
So yes, it's common for puppies to be born with white toes and like others have said, white patches in the chest area. My friend owned a rich bi-color GSD (all black, tanned legs) but he had a white tiny patch in the middle of his chest, that stayed though.
Even as babies though coats always change, some stay the same, most do not. My friend owns a Shiloh Shepherd and her coat changed drastically.
Not gonna lie, I'm a fan of the white toes, it's adorable.