I'm sad. -Backstab.

Doesn't the school keep some information such as their email,phone number,etc on the school website or school main office?If you try hard enough you'll find him in person again.Most teachers stay as a teacher 'til they are retired since they become so obsessed with the idea of "passing it on"(giving knowledge for the future).Besides,its never late to say hi.The teacher may have not even bothered befriending you on facebook since some state laws require teachers to NOT be TOO social with kids who have not graduated from high school;any social activity such as taking kids out to dinner,going to their house, or befriending them on facebook or kik can get them in trouble.So there is no rational guilt or sadness to feel.