DSF

might be worth asking MDP direct
i've had a few tech issues/questions lately and they put you thru to Ireland usually
and i've found they are really helpful and friendly

I had the same thing happen to me with some softshell jackets. White vinyl on black jackets. The looked great when they were completed but over the next few weeks the White gradually changed to a grey. Ended up with them back and giving a refund. An expensive mistake but still don't know why it did it - it must be to do with the way the jacket was dyed in the first place.Look forward to reading about your solution.