I just cleared my Firefox cache and now it looks as crisp as it should. Also checked with Chrome. But that's a strange phenomenon that never happened before... Why would Firefox make JPGs out of PNGs?! We’ll never know… Anyways sorry for any inconveniences my comments might have caused you!
The WIP looks fine indeed. Somewhere along the way your final was a JPG once. :(
I boosted the bightness so it's clearly visible: postimg.org/image/962ljvbk7/
Looks like this once was JPEG-compressed so there are a lot of funky pixels in the dark…
It looks very nice as a whole, but it slightly baffles me how you managed to use 10 colors.
It has some rough edges here and there, but not bad at all. :)