As it is a tendency to just click away without as much as remembering what I did, I still have to re-create it. But I'm at a design studio right now and helping out these friends who got a work-overload.....
The image was created at 72 ppi. I created 2 layers of color, used the pen tool to create the shape over one layer, then MENU>SELECT>FEATHER... used a feather radius of 20pixels, made a copy from the top layer through that selection by LAYER via copy. If you hide the full color layer, you'll see the gradient.
My next idea was to do it with the other layer..... CTRL+click gradient layer , CTRL+SHIFT+I to inverse the selection, make the first layer active then create new layer via copy.... so now you have 2 color gradients.
Making copies of the layers so I can have intact original to use in case of "accidents", I plan to use either transform tool / Smudge on parts of curves to create the elements for the animation frames .
To get sharper gradients, I would suggest lowering the feather radius. That would make the gradient sharper. And when you deform say.... part of the "thumb" in the image, the gradient will stretch and spread evenly.
Another trick would be to make a copy of a "thumb".... CTRL+click layer to select the part, go to the feather controls and increase the values, invert the selection and hit delete. This will increase the gradient. Without deselecting, hit the delete again and youll have more effect on the gradient. Use transform to match the edges with that in the lower layer. Then select the lower layer and erase the underlying parts of the image and merge.