I agree with Perna - you can take too much vitamin D and suffer physical affects. I suppose we can become addicted to anything, we perceive is giving us a benefit but its not an addiction like a narcotic. Usually the amount you were prescribed, should only be given for a short time and you shouldn't take multiple doses if you forget.
Vitamin D is a 'Fat Soluble Vitamin' - this means its stored in the body and not excreted in the urine like some other vitamins. It should also be taken with the main meal. Speak to your doctor, as to how long you're supposed to be on this supplement and only take it as prescribed.

http://www.mayoclinic.com/health/vit...icity/AN02008/

http://www.livestrong.com/article/43...water-soluble/