It might be something to do with flash. In photoshop, try to make all the frames as layers in one file, and then save it as a gif. You should get a message asking what frame delay you want. Make it the amount of milliseconds you want, and then save it. That's what I do.
Lovely idea! I agree with Lin, I think that, the more color shades you have in jpg/png files that make frames of GIF file, the more grain you tend to have after you safe file as gif. I am making GIFs for quite a time, and from my experience using as little color palete as it's possible helps to avoid things like this