Ghost?

When I can be bothered, I ride up to Hampstead Heath in the morning, do my Tai Chi and take a picture of the bench opposite. pictures of bench.
This particular day, I sat on the same tree trunk as usual, took the picture, glanced at the back of the camera and immediately took another picture.
This is not photoshoped or changed in any way from when shot. I have been a photographer for 30 years and have never seen flare like this. I have tried on numerous occasions to replicate the same effect, to no avail.
I'm quite happy whether it is or it isn't, but it 's weird.
NB There was no one else there and I don't smoke...