also i would call vet and discuss if he said this could be a concern. i always worry about picky eating with this breed as it relates to liver shunt but do not want you to panic as could just be getting adjusted to new home
mine are all 6 now so maybe some of the breeders and new pup owners can share more as it has been a while since mine were pups but i just remember dex getting hypoglycemic and scared me - he was fine once we got pedialyte and nutrical in him and before i got it i rubbed his gums with honey - he was about 2lbs back then too
i recommend having pedialyte unflavored and nutrical in fridge ready to go