It has happened to me as well. But I think this was done for safety reasons rather than because A3 was concerned about A3*Gs irritation... There would have been plenty of much easier and straightforward ways to deal with that if they cared Most likely nobody was willing to pay 16 euro (or whatever is they needed to pay) to get more legroom on a 1.5hr flight. Somebody was required to sit by the emergency exit, and they chose you.

There is good reason why even LCCs free up these seats on OLCI a couple of hours before departure, if they are still unoccupied. Which is yet another signal of how sloppily implemented this new seating policy is...