I am not sure if this has been covered here before... I am having a problem with a number of my shirts. The collars, mostly at the point where they fold down, seem to be discoloured. I have no idea why this is happening. I always wash them in cold water on an easy cycle, iron them when they are still damp, and always make sure the iron is not too hot (in fact I rarely iron the collar in fear that it may cause the discolouring). Any thoughts as to what is going on?