I got a wonderful tip from a fellow artist letting me know that I could remove some of the dye splotches by pouring boiling water over the offending spot. Undeterred- I figured that I was simply going to take my half-quilted piece and immerse it in boiling water. Which miraculously took the spots out. Whahoo.. I hung the quilt out to dry in the 104 degree heat we were having and decided that from now on working with dark fabrics is the way to go.
I retrieved my half quilted piece from the sun, and saw that while I had gotten rid of the offending spots, I ended up with some mottling on my yellow fabric. And luckily I really really like the effect- even though it was completely happenstance.
Lesson here- either I am a fool and should not have wasted the time on this little study once the dye started causing problems. OR I am one tenacious beast. I prefer to think the latter. And now back to quilting!