Promotion faill

So I just went 3/2 in my promos for plat 5. Not to bad, one would say, however, at the end of my fifth game instead of being greeted by the message that tells me i have been succesfull in my promos, it told me that i QUALIFIED for a serie?!?! Does anyone have any idea why this happened, or what can I do about it, or is it going to happen again?.... I would really apriciate any help