Yes, of course they just wanted to accommodate the couple. It comes down that basically they won't tell you the TRUTH in case you make a fuss. So they come out with the bog standard:
- Double booking
- Computer glitch
- Operational reasons
If you have good reason to select your seat, you should mention that you specifically chose that seat and that nothing was said at check-in.
On one occasion, an airline tried to split my wife and I in order to accommodate another couple! I told them to find another solution. They did