Hunger is a sensation dependant on several factors, only one of which is actual lack of caloric resources. For example, one of the biggest influencers on hunger is hormone ghrelin. Its secretion can largely be "trained". So, if somebody's lunch time shifts for a couple consecutive days, this hormone secretion also changes to that time.
In general, hunger is not the best indicator of when the body actually needs food, more of when our brain expacts it. And usually our brains expact food after particularly resource-depleting tasks, e.g. physical labour, exercise.
Side note, how many people notice that they often don't feel hungry during the training session, but start right after it? Almost like our brain knows that you won't start eating mid-set, so he holds off that signalling until after the session ends.