I watched several more hours of TV after my above post, and did not see the symptom again. Although I didn't watch any content that had any predominantly red scenes either. Somewhere between NBC and my eyeballs there was a piece of equipment that could not handle red picture elements. The 811 is still my primary suspect.
I'll just keep my fingers crossed it was a one-time fluke.
I'll just keep my fingers crossed it was a one-time fluke.