Kaira, we learned that even at the vet's office, people do not use common sense. My dad had Teddy on his lap in the waiting room while Max and I were in the exam room.
A woman came in with a very large Golden Retriever and purposely dropped the dog's leash so that he could check out Teddy. Dad told the woman to back her dog off, and she just laughed and insisted he was friendly.
Not everyone wants to socialize, especially at the vet's office.