Originally Posted by Andrew Yiu

Actually you'll be surprised how many people stay up just to call in for their upgrades... no advantage for us to close off a flight to 'play tricks' on our tier customers if your upgrade is going to clear anyways. The only time we would close it off is if we think we could sell the seats for revenue. Since your upgrade did clear 4+ days before departure, it was obvious in your case that we went ahead and released more seats afterwards after the initial batch was gone.