I managed to catch my girl holding her head up while she's on her belly! This doesn't happen too much because she gets really mad and throws her head down in protest while flailing her arms and legs. I'm pretty sure that she would pound her fists and yell, "Not fair!!! Not fair!!!" if she could.
Being the tyrant I am, I make her do it anyway. :) However, I'm always there to distract her!