It's something many pixel artists try to avoid, it'll look like this: http://www.locustleaves.com/spelunky4.png. You have it specifically on the far right and left roots with both the darkest and second darkest shade. Also, maybe getting rid of the palette could help push this into the gallery faster. ;)

 Thanks, but what do you mean by "banding"?:

Very sweet, though you got a bit of banding happening