Larry I see that on some almost every year and don't worry about it. I've blamed it some on leaving them too long till they split and then at times felt that the light when hanging when split might be the culprit. I usually only see it on cloves that have split open. I have planted them and they do fine. Jay

Thanks, Jay. These are hanging on the north end of my "lean-to" type of shed. There is a 6' door on each end, they get light but not sun.