I didn't see the phenomenon, but it would not have been the "Green
Flash".

The Green Flash is an effect sometimes seen when looking at the sun
itself as it sets (or rises) and not when looking away from the sun.
Seldom seen from the ground in Britain but often seen in other places
(eg Antarctic) and indeed not infrequently when flying (I was lucky
enough to see many green flashes during my flying career)

Jack