Interesting situation from EF this morning. I have a trip for 2 people this summer PHL-LHR-PHL and I already upgraded the outbound. Several months ago I put an alert on EF to notify me if 2 "C" seats open up. Later on, I added another alert for 1 "C" seat figuring that I would be willing to divide the reservation. Anyway, this morning when I woke up, there was an email from EF saying that 2 "C" seats opened up. Interestingly, there was no email saying that 1 "C" seat was open. Also, when I then checked EF there were zero "C" seats. That makes me think two things. (1) Someone must have grabbed 2 "C" seats very quickly on that flight and (2) EF must not be searching all alerts at once - in other words, EF looked for 2 seats and found them, and then later on looked for 1 seat and did not find them (because the "C" seats were gone). I think that is the only logical explanation.