Yes I would expect my child to be offered something to eat, even if it was some bikkies & milk. BUT Saying that, I am use to my kids helping themselves. So I would quite possibly forget if the kids where busy playing. Had they been home to the other parents place or where they out the whole time?

So YES I 100% agree that he should have been offered something.. Maybe its a good time to teach him how to politely ask (he shouldnt have too, but you know...)