Do you wear sunscreen? I've noticed that will turn the leather white on both of my cars with dark leather interiors. Real POA to get clean, most conditioners won't take it out. Haven't had to do it to my car yet, but on my wife's car, I had to use a mild soap solution to remove the sunscreen, then re-conditioned the heck out of it when I was done.
2008 550i, Carbon Black, Black Dakota, 6MT, Sport Package, Nav, Logic7, Comfort Access, Cold Weather, Folding Rear Seats, iPod SOLD, but not forgotten