Something's fuzzy here, but it isn't the navel. I think your shutter speed was slow enough to get a twitch blur. Either that, or your resoulution is just too low. It's a good concept for the challenge, though.
This looks like it did not get compressed correctly. I don't know for sure what happened but on my screen it is blurry and has jagged edges around words and things. The photo itself seems to need a bit of straightening.
Composition: Subject Placement, Cropping, Background 5
Technical: Focus, Exposure, Lighting, Processing 3
Appeal: Is it Interesting, Motivating, Etc.? 3
How well does it meet the challenge: 4
Total Averaged Rating 4 Autool