I was looking at a tooth in the back of my mouth with a flashlight and i noticed there are dark red veins on the back of my throat. is this normal?

Veins in throat: Yes, this is relatively common. Some people have more of this than others just like there is variation in many things in different people. I would recommend seeing an ENT MD just to check it out and make sure is no concerns.

Probably: Make an appointment with your Dentist to do 2 things: 1) Examine the back of your throat and, if necessary refer you on to an ENT, and 2) Examine the tooth that you were trying to see with the flashlight.