You're welcome :p
Another thing that can be improved : banding
The principle of pixel art is just use the least colors possible. In your case you use some colours almost identicals, like the gray 98 and the gray 99. Human eyes can't see the difference between this two colors, so why use two color rather than one?
It goes against the base of pixel art. I think you should revise your palette if you want that your pixel was approved.
Your opinion is wrong. The color space of the editor -256 colors, I wanted to make black and white, grey image. It is the right of the artist to choose 2, 10, 20, 27 or whatever arbitrary number of color shades. RGB, Grayscale; Gimp, Paint, Grafx2, Minecraft; the mouse, graphics tablet are tools. The principle of pixel art-drawing through the pixels, this condition conforms to my work.
My work is not a picture reduced to the desired format - is pixel-art, made pointwise.
Why use 256 colors? oO
In this case ~20 colors are enough. I think you didn't fully understand the meaning of pixel art :p
251 colors for one frame, with a grayscale palette, there is a problem...
This looks like a lossy compression.
And the frame 19 can be removed, it's the same than the first frame ;) (this creates a saccade)