I’ve been in a similar situation twice.
The first time happened right after I joined the Navy and was going to Orlando for boot camp. The plane was a DC-10, and there were three other passengers: all girls recruited by the same recruiter, heading out to boot camp. When we arrived at recruit training command, we were separated into two different companies, and I never saw the two who ended up in the other company again.
The second time happened when my husband and I were returning from Spain after spending three years stationed at Rota. For a number of reasons, we were delayed in arriving at the airport in Madrid and missed our flight. Anyway, long story short, we ended up on a flight on a DC-10 with three other people. The service was amazing. What I thought was interesting was that the crew offered to move us to first class, and we declined the offer. So did the other passengers. None of us had paid for first class...
The offer to move you to first class was based on two reasons, good PR and to make their flight easier. Less trudging back and forth with every one contained comfortably up front.
Should have treated it as a gracious gift, as all costs to carrier were fixed regardless of where you sat. The surprise benefits would have been mutual.
You DECLINED a free move to first class? Must be the first and only time in the history of commercial aviation!