Maybe I wasn't clear. On the eastbound flight, EWR-KEF, departure was at 8:50 p.m. Although very few people wanted to buy food, the FAs offered drinks for purchase to every row and many people bought them.

The mixed-up service was on the westbound flight, KEF-EWR, with scheduled departure at 5:00 p.m. Iceland time, actual 5:30 p.m. So the flight was within the dinner hour, even for Europeans who might have wanted to eat late, since it was 7:30 in continental Europe.

But I had pre-purchased food. That is, ordered and paid for it in advance, as had many other people. Advance orders of sliders were served pre-emptively at the first possible moment, about 5:45 p.m. Most paid-for orders of chicken, in the back of the plane, were served pre-emptively around 6:30 p.m. I was the only passenger in that part of the plane who had to request his paid-for order. It would make sense to me if everyone had to request their food when they were ready for it; I'm not sure that everyone who received their sliders at 5:45 wanted them that early. It would make equal sense to me to serve pre-ordered food row by row in order to complete it systematically.

I still think it was strange that drinks for purchase were offered to some rows where there was no food order to deliver, not to others. I suppose it is possible that some passengers signaled the FA with a gesture or twitch that I didn't see.