It is normal. You will receive your FP soon. I submitted my I-140 to NSC November 2004 and my I-140 was approved June 2005. I then submitted my and my wife's I-485 June 2005. My wife recieved her FP notice March 2006 and I got my FP notice April 2006. I think if you submitted EAD application with your I-485, you might receive FP notice a little earlier.