Upgraded ET - CE on Saturday, LHR to MAD on a morning flight. I was particularly pleased since this was a 'day trip' fare which only cost £89 for the return trip!
Interestingly, my travelling companion on a separate PNR was also upgraded and after we both watched our seats move to different parts of the cabin twice on the app, we ended up seated back next to each other again. He's on my friends and family list, so perhaps whoever did the seat swapping picked up the link from there?