Changing "slide to unlock" animation

When on the lock screen, you are usually presented with the slide to unlock text showcased with a nice animation. However, on my iPhone, the animation oscillates between two differently designed animations. One (1.) is more faded and gradient-ized and the other (2.) being newer and silky. I am confused as to why this is happening. I am running iOS 7.1.1 on an iPhone 5.