Poets are known for bending rules for better rhyme or rhythm, so poems and songs are not 100% reliable in this regard (word stresses in poems are particularly "fluid"). But I agree that "спросила кроха" sounds natural enough, even if it's incorrect, strictly speaking.
Still, the question was if "сладкий крошка" is possible from grammatical point of view. It is, even if it might sound weird.