If you'd been on DL or AA, I'd have had a strong suspicion your flight ended in an odd number, based on the FEBO theory; that is, the service starts in Front on Even (numbered flights) and in Back on Odd. It's an acronym Lex and I invented and posted on FT some years ago when we were DL flyers, after an FA told us that that's how they were supposed to do it. We later heard that on AA the FAs actually tend to stick to that rule. On DL it was hit or miss then, and in recent years we hardly ever saw it.

On NW we've almost always just seen service from the front to the back. But interestingly, on a recent flight we had a FA come quietly to us in row 3 and ask our meal choices before anyone else. I guessed it was because she'd seen she had 2 PEs.

What I now realize is that, because we prefer bulkhead seats, it's hard to guess if FAs might be giving PEs early choices or not.

On the only other recent flight where we weren't in the bulkhead, we were in row 4 - no choices left by the time the FA got to us. Horrors!