I very recently installed a set of Hilo low g's with wound 3 and 4 on my tenor. This is the first time I have used wound strings. There seems to be a difference in the wound strings because th G string is starting to show rust spots all over it, inluding on the headstock and bridge where my fingers don't touch them. There are no signs of rust on the C string. Is this normal? Have you found this on all brands of wound strings?