When you plan way ahead in the airline reservation process and you request an aisle seat in an upgraded section of the plane, you are baffled several weeks later when you get an email from the airline regretting that they have to change your seat to a middle one two rows back.
Originally, you are cautioned by your tour company that the airline might not honor its requests, and aisle seats are in demand.
It's doable, yet it's not what you were hoping for on the longest leg of the overnight trip. It seems silly to upgrade your ticket, and not have an optimal seat.
A couple days before departure you have the foresight to check your reservation on the airline app, and out of curiosity pull up the seating chart. Your original seat is now available along with two others.
With one click, you are good to go.
You are assuming the airline held that seat out for a premium fare, or someone changed plans at the last minute.
You don't know about the games airlines play.
Was it luck, or something more complicated in the reservation system?