I think it is a "Bi-Level Die Crack". I just read this on error-ref.com and it describes this coin. It is no where near as dramatic as the one on the site, but it describes what I am seeing. Here is a pic of mine and the link:
http://www.error-ref.com/Bi-level_die_cracks_.html

http://www.error-ref.com/Bi-level_die_cracks_.html
























