Hello TBearSF,
Thanks for asking the Apple Support Communities for help with the strange reflection in your picture.
This would still be considered lens flare. It depend on the angle of which the light source is hitting the lens as to what part of the photo this actually shows up in. A lens flare depends on where the sun (or light source) is, where the lens is pointed, and then the reflection ends up anywhere within the frame of your picture.
This article has some info and mentions moving the camera slightly, which you have since the other shots don't include the same reflection: If you see a flare, haze, or spot near the edge of your photo or video - Apple Support
This link has great information and links to other articles to help you find the best camera mode for different scenarios, as well as how to take the perfect photo: Apple Photography
Thanks and have a wonderful day.