I recently went thru a box that my mother had.....fabric was folded in the box (not a plastic bin) for probably 50 yrs. The fabric was just fine!!!!!! That being said ---- I wonder at the difference of our fabrics today compared to the fabrics 50 yrs ago. With the chemicals they add nowadays, I wonder if they'll last as long. You rummaging around is just fine. I, too, would not want to refold everything. UGH!!
Others mention mildew....I live in the high desert....we don't have mildew problems....but if you lived in Astoria Oregon (average 55 inches rain per year), you know that mildew can happen at any given moment. So --- rummaging around in your fabrics, not putting them away damp, and getting busy sewing will prevent the problem!
Also -- the experts tell us to not store our quilts in plastic......It dawned on me the other day that storing my fabrics in plastic bins is the same as storing a finished quilt in plastic!!!! I've been busy removing the bins and stacking my fabrics.......UGH - what a job!!!! Guess I'd better get busy sewing!