Where do you people get your facts? No, tattoos shouldn't need a touch up, that is not a dirty little secret. Rarely should a tattoo need a touch up. If they do need a touch up, most often they are done as a courtesy because the artist guarantees their work, because they desire people to carry their work with pride, and they want it to look good of course.
And no, you shouldn't go back 30-45 days after the tattoo is done. I guarantee my work for 6 months, in that time, I will touch it up if it needs to be. I will not work on a tattoo 30-45 days after it was done, it's not completely healed. The longer you can wait to get a touch up, the better.
Now, as far as your tattoo is concerned, it is possible for your body to reject some of the ink, but it is rare, and is due to some of the impurities in the ink. Tattoo ink is a foreign substance, and when your body heals, it can try to reject it. I would have to see the tattoo to be able to tell if you're rejecting it or not. Most artists can tell if it is from poor after care or from the skin rejecting the ink. But, it sounds to me like you didn't heal it properly. Do you have pictrues?