An old class mate?

I was sitting in the waiting room for my first appointment with a new dentist. I noticed his diploma on the wall, which bore his full name. Suddenly, i remembered a tall, handsome, dark-haired boy with the same name had been in my school class some 30-odd years ago. Could he be the same guy, way back then? Upon seeing him, however, I quickly discarded any such thought. This balding, gray-haired man with the deeply lined face was way too old to have been my classmate. After he examined my teeth, I asked him if he had attended Chester high school.
'Yes. Yes, I did,' he gleamed with pride.
When did you graduate?' I asked.
He answered, 'in 1975. Why do you ask?'
You were in my class!', I exclaimed.
He looked at me closely. Then, that ugly, old, bald, wrinkled faced, gray-haired, decrepit man asked, 'what did you teach?'