Chocolatiers refer to this as a bloomed chocolate, which is a wonderfully obscure and appealing way of describing the white stuff that forms on old Halloween candy. There are two processes that could be happening here, either sugar bloom or fat bloom. Sugar bloom is the candy world’s way of saying sugar crystallization. If your candy is exposed to moisture, sugar molecules dissolve out of the fat in the chocolate and once that moisture evaporates, the separated sugars have a chance to crystallize. If your candy has stayed dry but underwent a quick temperature change or was stored warm, it’s probably fat from the cocoa butter that has separated from the chocolate. In either case, it is usually still fine to eat.