My friend has two separate round trip tickets, JFK-RDU and JFK-HND-PVG and on the way back from RDU he tried to get boading passes at JFK airside and was told to go out of T8 and get the boarding passes outside security and then come back in. He has no checked luggage except for a laptop backpack. Is it because he has to go through custom before leaving JFK? His laptop has already been security screened at RDU. Would it made any difference if he doesn't even have carried on backpack?

Thanks.