I think i have figured it out now as when i animated the wave taxtures i seemed to have animated by different values even though i thought i had used the same values. when i re did the key frames for the animation it fixed the problem. (I hope that makes sense if someone has the same issue, basically make sure the end keyframe for both wave textures is set to the same value e.g. 8*pi not one as 8*pi and the other as 10*pi)
