I would get rid of the head around the collar. and maybe make a little more space between the heads.
oh by the way can you tell me what you think of my design http://www.threadless.com/critique/73720/Troy
I'm not 100% sure, but maybe Threadless has rejected this because of this:
A belt printer uses huge screens that cover the entire front and back of the garment.
One thing to keep in mind when designing for a belt
printed tee is that the colors used in your design
should never touch each other because registration is
never exact. For this reason, one-color designs are
recommended.
Seen at the Specialty Printing.pdf file into Sub_kit.zip