The aluminum might have something to do with the possible AA purchase of 320's. If you get all the aluminum from the same mine, you dont have to paint them grey or anodize the panels so they are all the same aluminum color. So AA can keep them bare to save wait. No aluminum mine in the EU is big enough for Airbuses so if you keep it bare it looks like patch work. Remember the A300s? The painted ones were leased and the aluminum were owned but had to be treated.