I had a green like that once. Seemed fine after prewashing but I had green fingers any time I worked with that quilt. Washed with color catchers countless times and there was still dye coming from that fabric. Finally gifted it with a box of color catchers and instructions to ALWAYS use them.
Since then, on here, I've learned of Synthropol (sp). I've not used it but I would suggest doing a search here on the board for more info. If I'm correct, it suspends the loose dye so it does not migrate to the other fabrics.
Good luck.