Yes it does happen occasionally.......as above poster said "schedule opened up on the day a new sale was announced". Sign up for email notification of sales, etc. and check faithfully every day......I've had nonavail. fares open up several times in the past. Typically, as you get closer to your travel dates (not super close, but, maybe within two months) and only the lowest fares have been sold the airline will open up more seats at the lower prices. I've found if all fares but the two highest are showing as unavailable you're usually out of luck and I book another flight. Keep in mind you could always book a different flight at the lower price and if the one you want does open up just change it.......SW doesn't charge change fees, but, you will then have a credit (ticketless travel fund) that you'll need to use within one year of the original date you first booked.