I used a version of the RippleAnimateUVVertexShader and the TwoTextureVertexColorFragmentShader from this Starling Extension Graphics Example:
The vertices are moved slightly up or down to create the wobbly effect in the VertexShader, ensuring that we didn't need to regenerate the underlying vertex data of the NaturalSpline that I used from the GraphicsEx part of the extension.
I then created separate Shapes for each transition between each bet lines, ending up with 9x9 or something different shapes, where each constituted an intermediate step between Line A and Line B
I generated them on startup, and when the time came to move the line from one position to another, I just addChilded each line Shape as it progressed between Frames.
Very simple to do, didn't use a lot of memory (The vector shapes are pretty memory friendly) and the effect looks nice. Also, since I didn't create a new line each frame, I didn't have to worry about performance very much.
Not sure if that helps any. 🙂