engine makes metallic ticking sound

Maybe 30 percent of the time, at idle you can hear a definite metallic tick similar to loose rocker arms that I have dealt with on my 87 camaro. Every time I have had it at the dealership, I mention it and they say that its normal for my engine. I have a degree in automotive tech and have built motors in the past and this is not a sound that any engine should make. I found a star bulletin online about it, and it claims that the valve retainers will rotate into a position that allows them to contact the valve spring and make the noise. They claim it will not cause any sort of failure and outline the procedure to correct it but it will eventually rotate back and make the noise again. As soon as my drivetrain is no longer under warranty, I will do this myself. Its embarrassing to be in a drive through or next to another car or building and hear this offensive ticking similar to an old car with an exhaust manifold leak, especially when I paid more than $30,000 for it new.