I don't know if it's "normal"...but its exactly what my son did.
Fast forward...we found that milk + food worked even better, but that he HAD to have milk immediately, even though sometimes he would fight it. It became our routine; wake up crying, scoop up into cuddle time with milk and a snack, or milk and a meal = Happiest little boy on the planet.
Fast forward...we found out he's hypoglycemic.
We didn't find out until he was school age, because we always gave him milk whenever he asked (as well as when he woke up) and he had his own "snack drawer" and shelf on the fridge filled with things that he could eat whenever he wanted. We did this to encourage healthy eating habits, and as a way for him to feel independent (even though, obviously, we're the one's buying the food and stocking it).
We had had hints if we'd known what to look for, but didn't recognize them while he was in preschool, so we didn't find out until he was in school full-time. (guilt guilt guilt guilt) (did i mention guilt???)
Its reeeaally easy to control, and milk is one of the best ways: the lactose hits immediately, the proteins are a little later, and the fats a little after that. YAY. We tried sending juicy juice boxes to school, but they really didn't work nearly as well.
In any event, its something you might mention to your pediatrician...and to keep an eye on yourself. The hard thing, of course, is that MOST children get cranky when they're hungry. :P
Of course, I wouldn't say your son's hypoglycemic just because ours did the same thing...but it took us so long to find out (because we were doing the exact right thing on ACCIDENT!), that I'd feel even more guilty if I didn't pass it along.
So... "Oh yeah! Us, too!"
From our side of the street,
Z.