Take a look in the gorcery store. See those tubes of rolled oats? The tubes are cardboard and the oats sit at room temperature. How bad does the oatmeal taste? How bad does it taste if you have it sitting on your shelf at home for a month? How about 2 months?
It really takes quite a while for crushed grains to develop a stale flavor. I've had crushed grains sit for a month with no problem.