Is graduating on the August a problem in admission for PhD programs in the U.S.?
It never hurts to specifically check with your undergraduate advisor and the desired graduate school's admission office just to make sure. My understanding is that as long as your current university acknowledges your completion of the undergraduate program (regardless of whether you physically have the Bachelor degree certificate or not) prior to you officially beginning your graduate program, then there should be no problem. But like I said, you should check in with your undergrad advisor so that they can inform you of any lingering policies or concerns.