there probably never was a better price (when you bought the ticket)
I don't think you ever had a $300 savings. If the lower fare existed at the time you purchased your ticket you would of paid less, but it didn't exist.
You might want to consider waiting until the last minute to book your next trip to see if you can get a less wxpensive deal, but beware if thw flight is sold out of inexpensive seats, you could possibly pay more.
RC