When I was back from my trip (NRT-YYZ-YUL), I did OLCI 24h before going to NRT airport. Saw the ''eligible for upgrade'' button. It was a green button. I did not know what would really mean and if it was really for an upgrade. I just printed my BPs. While checking-in at AC's EC counter, I asked to the agent if there were any available seats in EF. I didn't ask to be upgraded, but she upgraded me by printing a different BP.