About 15 Years Ago My Boyfriend Donated Blood And Received

About 15 years ago my boyfriend donated blood and received a letter saying it had been rejected because of antibodies they found in it. When he called them they told him it was nothing serious probably just his body trying to fight off a virus. What does this mean. He has always been exceptionally healthy and has had blood tests since then for preop and annual physicals as well as insurance exams with no mention of any problem. What could it have meant back then?