Learned a lesson yesterday. Always look at your boarding card if they give you a new one. Yesterday while boarding my ET flight in 12F from OSL to LHR I scanned my mobile boarding card as I always do. The gate lady said "I am giving you a paper BC". I thought it was i little odd, but didn't even think it might be an upgrade, so didn't even look at it. It wasn't until after the flight I took a closer look just to see it said 5D, instead of 12F, lol. I noticed there were 8 rows of CE so I just assumed it was a busy flight in front of the curtain, and it didn't cross my mind that the paper boarding card she gave me wcould be an upgrade. And even more odd that she didn't say"Congratulations sir, you have been upgraded", instead of "I'm giving you a paper card".
Now I also noticed that the flight hasn't been credited to my account yet, so I am thinking maybe it has been recorded as a no show?