I have seen that happen locally when guys cut and bale the next day because "it's dry" and the stem moisture is still high enought to make it mold..  That's why I wanted to know how long it was down before baling.  I know this year servera guys were super excited about cutting and baling the next day in an area where it typically takes 3 days to make dry grass hay; I avoid hay from them because I worry about runing into hay like this.