Its a shaders glitch, it affects all spherical shapes in toribash. Only way I know to fix it is to turn off shaders when you draw, or stay away from making any detail in the top (and bottom) 1/8th of the texture, and dont draw any straight lines within the top (and bottom) 1/4 of the texture to resist that pulling effect you see on the lines. (which basically makes any detail on 1/3 of the head worthless.) Either that or call hampa to make it behave like it does without shaders.
Here is kind of an explanation idk how true it is because it happens even on my good computer
http://forum.toribash.com/showthread.php?t=412359
notice how some of the curved lines become straight and the purple area on top just disapears? If you can think in polar coordinates with triangular distortions then you might be able to make a straight line ...