Congrats, it seems to work really slick.
One thing I noticed, which I wouldn't call a bug per se, but there seemed to be two different formats to the file selection/submission panel. One version split the files into Required and Optional groups, the other just listed all the files alphabetically by filename.
I preferred the split of files into two groups rather than showing in a single large group; it might make sense to have the map files (diffuse, spec, normal, etc) in one group and the supporting files (fullsizeimg, thumbnail, reference1 and reference2) split into a second section. I think it was a bit easier to use with a little white space in the design, but not a big
deal.