I'll  see that in  my piles that were  made on top of   wet or very cold soil..   or  rained on  before  finishing up the pile..   Something about the extra  free-water messing with  the fermentation process  we are used to seeing?     or possible late season cutting  when putting  colder  or frozen material  on the pile..   and the fermentation process is  delayed until the  pile's ambient heat eventually brings that layer up to desirable fermentation temp. 
methinks  there can be  layers that ferment on it's own schedule!!

yeah,  it looks  just like it did   when it was dumped out of the wagon!