Went to see/pick puppy...confused. :(

The breeder I'm getting my little lady from I put a deposit down on her after seeing some pics and speaking, at length, with the breeder about her personality and our home life. The breeder said that she was more laid back, not one to fight at the food, a sweetheart, and a snuggler/lover. So, we made the arrangement I would put the deposit to hold her because she sounded like such a good fit and then I would come see her today on the arrangement that the deposit could be transferred to another pup (which it still can).

I go see her and I'm not sure if I should be concerned or not. That's where I'm asking you guys.

There are a lot of littermates because two litters were born a week apart. She is in the younger litter so there is a litter that is one week older.

Either way - she always tended to stay out of the pack. Just off to the side and sort of wandering around. Not playing with the other puppies. When the other puppies attacked her (I saw it happen twice) she didn't fight back.

When I held her she didn't try to bite me or squirm. She laid calmly. She didn't seem fearful. Just very, very "meh" about everything.

Is this normal?

She is only 4.5w old so I'm not sure if I'm expecting too much but when I saw all the other puppies playing together and her just wandering around on the sidelines it made me wonder what she was up to. She never seemed interested in interacting??