jimmyp, I find that every processing solution changes color when processing color material. Fixers, wash waters, developers and stops all turn pink. The effect is biggest in the first solutions, dev and stop. I've deducted that sensitizing dyes come off from the film when processing, causing this, and it has no effect in chemicals. This is true to many BW films like TMAX as well. Maybe some products lose their dyes faster (that is, only to developer) than others.
In E6, there is no wash between bleach and fix. The same is true with Ilfochrome. Then again, with C-41, there is a long wash between them. Funny.