There is absolutely no reason at all. Purists will disagree with me but then maybe they also have more $$ in their pockets than I do. It would be a good idea to wash the sheet before using. (and you can also check out Goodwill or local thrift shops for gently used sheets. I just snagged 6 single bed top sheets in excellent condition for $8 each. They will be used on donation quilts for my guild, but I would have no problem using them on my own quilts too.)