Orange spots only in certain apps

I was listening to a podcast on my iPhone 5S when I noticed an orange patch on the upper right corner of the screen. I thought it was screen damage of some sort, but then I discovered it only appears when I'm on the "now playing" screen of certain podcasts. All 3 podcasts where it appears are from NPR, so I had my cousin, who also has a 5S and also listens to NPR, check his, but he has no orange coloring on the same app screen. It goes away as soon as I tap to another screen, and appears on screenshot (see attached) so it must be software rather than hardware?

I tried closing the app, powering the phone down and back on, and finally deleting the podcasts app and reinstalling it. The only change was that now on one of the three podcasts, the entire top of the screen is orange, while on the other two it's still just an orange circle on the upper right.

Can anyone explain this mystery?