I've been training my 1 year old budgie for the past month or so. At first I'd place my hand in the bottom of his cage and he would sit and watch it intently, waiting for predatory movement. He's realized my hand means no harm and will come towards it if I put some millet in my fingers. He has recently started doing something new though. If I hold out my finger with millet in my hand, he'll reach over my finger to the millet, no big deal we're working on it, but he will sometimes just start to nibble my finger up and down. It never hurts but it's fast consistent little nibbles up and down my extended finger. Is this him trying to say "Move this finger! I don't like it!" or affection?