I think you mean planchet and not flan. Looks like lamination peel to me. Let's hear from some better judges.
I think its die error. The metal can crack and make a patten like this when a small bit of the die has fallen out.
So was I wrong in calling it a flan instead of a planchet? I thought the two were interchangeable. Planchet vs. flan http://www.cointalk.com/t4306/
Sort of like the difference between a baby carriage and a pram. They are both rectangular boxes with hoodies on wheels but you find baby carriages in America and prams in England.