If that's true, then I highly doubt the OP could have saved much by switching. Full J on AFS flights is about half of what full F is. So if the OP was getting a 40% discount on F, the walk-up J fare would have saved almost no money. Now, let's look at a similar route with a 757, LAX-BOS. The full-fare for F on those flights is $1,149 o/w, so pretty much the same as AFS J. So the OP really wouldn't have saved much of a multi-billion dollar company's money.