Yes, this is something that happens to lots of varieties when the weather turns cold in the fall.

The older flowers, especially those that persist longer than usual, either sun bleach or perhaps moisture from rain, morning dew, or watering leaches out pigment found on the tiny hairs covering the flower.

`Cherry Chief' does this occasionally, and S. microphylla forms `Orange Door' and especially `Zaragoza' do it more or less routinely.

Rich, I believe that these partially white flowers are the more recently opened ones. To determine which, I will remove all of the currently open flowers from one branch and see how the next flowers to open appear. I believe that the Navajo series is your introduction?

Yep. Navajo Bright Red = Cherry Chief.

If this behavior remains constant, and the white pattern varies in the same manner as Hot Lips, I'd like to know.

Also, an image of the flowers might be nice if it is possible.