Why did i lose interest in things I once loved?

An example: I used to love television shows like Family Matters, Full House, Step By Step, and Friends...actually I was obsessed. Now I feel like I force myself to watch these shows when they come on in a re-run. They are not as funny or as entertaining as I remember. Now I prefer shows like Scrubs, Reaper, Tru Calling, and Prison Break. Am i just a freak, or does this happen to lots of people?