Are you sure it's not excess wax that's been forced out from between the strands? Some string makers use a realy stiff wax and it looks exactly like the strands are fraying. A new string can look awful darn ugly. Take a piece of soft leather and rub the string briskly. Heat the wax and burnish it into the string.

Now, sometimes string makers don't do a very good job of trimming the tag ends of the strands in a flemish string. If you're seeing ends of strands sticking up out of the braids, then that's no problem. Just a workmanship issue. Sometimes I don't trim the tags at all when I make a string. Use 'em as an additional string silencer.