I just saw a review on Amazon that shed some light on the fact that Amazon is working to fix the discoloration issue.
Edit (Oct. 16) - I received a very nice phone call from an Amazon employee today. They offered to either let me return this unit, exchange it for another (which would be my fourth), or make a note on my account and in a few months once the issues are resolved, let me exchange it for a proper unit. She reminded me about the one year warranty, and clarified that it would be covered under the defect clause, anyway.
It sounds like they might be re-evaluating the production process and realize it might take a couple months.