I think you should worry - palette control & design is a big part of Pixelart. You have many similar colors and some colors only used by 1 pixel etc. 10 min of work and you'll have this reduced to 32 (or even 16) colors with the same result. Learing to work with indexed colors and palette design will aid you greatly. Posting gfx that are or looks like 24-bit conversions will just thwart your talent (at least here 
). Then there is some issues with AA and shading...are you going for some kind of motionblur-effect under the legs? Otherwise it needs clean-up.
Ah, ok, I will see what I can do. And yes, I was trying to give the effect of soft edges on his back side to imply motion.