My 4 1/2 month old Kir had to spend the day at the vet and her first time away from her littermate(sister) JoMo and when me Kir and my roommate(JoMos mom) got home that night JoMo hissed and tried to bite Kir and just sits away from us and stares. Is this normal? Kir and JoMo have always been very close. JoMo is the very loving and cuddly of the two. how long will this odd behavior last? :?