was shooting neighborhood cows through the open front passenger door. I was shooting into the sun. No flare, but there are reflections from the side mirror. I didn't use a CPL. It never occured to me that this could cause a problem. Live and learn. Just looked at it again. There is flare just below the left ear on the cow on the right
That looks more like a speck of dust on your sensor or lens.
Your title gave me the thought you were going to tell a cautionary tale about getting robbed or mugged!
Looks more like sensor cleaning time to me.