I have some crushed oats in a cardboard tube that have been sitting in my closet for more than a month. My wife used some for muffins this morning. The muffins were delicious. You may have some of these "rolled oats" made by Quaker and they can sit for months and still make oatmeal for breakfast. I think your crushed grains will be fine.
I was reading the Compleate Joy of Home Brewing last night and Charlie Papizan states that crushed grains can stand for months stored in the proper conditions. I trust Charlie, So relax, and have a Homebrew
Yep taste is the best policy. I like to vac seal and freeze mine and have had them last along time. I do date the bags before freezing and before use taste them ( a day before and to allow to rest at Room temp)