Is your puppy the smallest of the litter? From what you describe it sounds to me like she was having a low blood sugar episode, maybe she hadn't eaten yet? Did the breeder say she does it all the time?
The only experience I have is when we first got Brody he was (and still is) a picky eater and I'd have to put something extra on his puppy food, like a wet mixture to make him eat. Even today, (he's 3) I put a little chicken on top of his food in the morning so he'll eat . . .I don't know how he gets by . . .
he weighs 5 1/4 lbs though . . .It's just very important that you get them to eat because they do crash pretty fast at that age.