I was worried about this when Southwest changed my return flight time and offered me a 'free' adjustment to some other flight. Without knowing for sure, I just assumed they would apply bag fees to some or all of the itinerary despite their reassurance and indeed that was the case for everyone who did change. As it happened, the automated baggage kiosk knew that my flights were under the old no-fee regime, so no problems. I do recall being quite annoyed several weeks ago when their email about changing my flight time said nothing about bag fees. Regardless, I am finished with Southwest and now look forward to the dedicated customer service offered by Frontier.