If you have shares or at any time have bought something....
You will know that its price changes.
You can't call Ford Motor Co and say hey, I bought your stock for $20, now it sells for $12, can I have my money back?
Or, if your favorite grocer sold you apples for .50 / lb but now they have them for .40, do you ask them for the difference?
I know airline prices can be mind-boggling sometimes, but I think they have the right to charge you the fee.
Now, if you can still be $37 better, I would take that rather than nothing.