It's HOURS not CREDITS. Two semesters worth of AP credits is not equal to 8 hours necessarily. Most intro calc and science w/lab course count as 4 hours, but others such as microeconomics or psychology is only 3 hours. It would be more appropriate to say I received two courses of AP credit (which is 8 hours).
Don't sweat it. Maybe it means that you get to pick 8 hours worth of credits to count towards graduation (meaning you can cherry pick the courses). Regardless, contact individual schools and see what they have to say. You're worry over something that is 1) out of your control, 2) does not warrant worrying until you have all the facts. Just take a deep breath, if you worry yourself like this all cycle (and it's only really been 2 days since it's begun), you'll die.