Demo Ball Game Paddle not stoppping

HI

I am following http://www.raywenderlich.com/28604/how-to-create-a-breakout-game-with-box2d-and-cocos2d-2-x-tutorial-part-1 tutorials.
The problem with this tutorial is that my paddle is moving continuously event after I stop to touch it. It slides when I slightly touch it.
Why it is doing so and how can I prevent this?
any suggestions plz?