How to keep wool from fading?

Mrs.B6302007

I bought second-hand a wool cover that was originally sold on etsy.  I washed/lanolized and used it the other night and it faded (it's several shades of pink) on the diaper.  I washed it again today but the water is still colored from the fading and it faded a bit more on the towel when I rolled it.  Does this mean the wool wasn't washed prior to the cover being made?   Will the fading stop over time after several washings?  Or, is there something I can do to prevent fading?