Hi Hippie!!! Have you been planting more citrus and blueberries?
Probably grafted because it is a sturdy proven stock - usually the stock is not very good fruit so they graft the tastier fruit to it and get the best of both worlds that way. There are many professional nursery men on here that could answer all your questions about that stuff. I have never tried grafting though so that is just a tidbit from reading. ~J