Normally all the cats knead when they feel contended and with their front paws start pushing the surface on which they are standing. Kneading always comes before a cat is trying to sleep and generally cats purr while kneading. It is very common among kittens and they do this when trying of feeding on the teat of their mother.
Kneading is an activity done by the young kittens. While suckling his mother the kitten kneads the stomach with its paws to stimulate the flow of milk and it is done once after every 2 seconds. This is called as â€œmilk kneadingâ€. Now the kitten purr and gives the signal to his mother that everything is fine and he is feeling contented. When the kitten grows they have their childhood remembrance with them. That is why they sometimes climb up to you and starts kneading as you appear very relaxed and contended to cat. Also if you had bought a kitten when it was very young then a kitten can take you as his mother because a cat shares only one close relationship that is with his mother. They knead their mother not only for milk but also to get affection and attention
Some cats push and pull the surfaces that are very soft like carpets, bedspread, their own bed and even on you with their paws to make the place more comfortable for themselves. They also purr while doing this activity as they feel fully satisfied. This happens with the cats that are very kneady. You should also feel nice as your cat is sharing its happiness with you.
Some people believe in other theories about kneading is that the cats are weaned too young or some says that they are weaned too late.
For whatever reason a cat kneads one thing is sure that kneady cat is a happy cat. And there is nothing to worry about it because kneading is a natural behaviour of cat.