am i just paranoid?

i just brought a new puppy home from the pet shop and he's been here 3 days. he sits a little funny so i think he may have hip problems! he runs fine and he does other activites well. he's only 2 and a half months old, but i'm still worried... am i over reacting or should i be scared? he has a vet appointment in 5 days so i will mention it then..
thanks for anyone's help!!
~worried puppy owner...