Originally Posted by
cavemanzk
What I'm getting at is, if you put a short term sale fare on. Stick to it let it run out. Don't going undercutting it on the same travel dates/flights as people have just booked.
Without knowing what fare / route you booked, it's entirely possible that they didn't undercut their sale fare - they may have simply had additional inventory added to a lower fare class. E.g. you bought S class but K class came available (due to cancellation or inventory management).
Airline inventory is very dynamic. The best approach is not to look at the price for the same itinerary after you've paid.