I have 3 sets of sheets, a summer set which is light blue pinstripe, a winter set which is blue, white, and red flannel, and a backup set that is all white. The white ones are rarely used and are stored in our hall closet. Our dryer broke and I needed the backup sheets but when I pulled them out there were rusty orange stains all over and they are a nice shade of yellow. The closet has no light and they were stored on a wood shelf. Our house is really old and we have only been here two years so I don't know if it is something in the house that did it. I have never seen any staining on any of our other sheets or my other white pillowcases we use all the time. The only difference with this set than the others is that its is in the closest and rarely used. Now I feel I can't use the closet and it is the only one we have upstairs. What could be causing this?! We do have high iron water, but we have a softener and don't have a problem with yellow water unless using the hose. I rarely use bleach because I know it can lead to yellowing. I don't know what is happening.