Colour Fast

In the past I have tested my home dyed threads by wetting them and ironing them onto white cloth. They appeared to be colour fast. Now I am pretty sure they are, because unloading the dishwasher just now, I found a hank swinging from the top rack, its colours just as bright and fresh as when I first dyed them. Don't ask me how it got in there; all I know is that it was thread I was using until quite late last night because Bossman was watching Man U, and I can only think that it was on my person somewhere, and fell into the dishwasher as I went to put my nightcap mug in before going to bed.