I have always been told purebred angus are homozygous polled, so any cross with a purebred angus should be polled. Some of resulting calves will carry the horned gene(heterozygous polled). Today with our knowledge of DNA there are always mutations going on and always have been. I really doubt the angus breed wants another genetic defect that causes calves to be horned.
Nortexsook, your bull is an awesome specimen for the Hereford breed. I have looked him up on AHA numerous times and the blood runs true.