How much ethics can a two-year-old understand?

Our daughter, at this point, still falls asleep in the same bed as we do. However, as she has grown very rapidly the bed has got too small for the three of us. Particularly as she has the habits of taking at least one large teddy bear to cuddle as she falls asleep, of sleeping sideways across the bed and of moving around so much that she ends up kicking us in our faces. So, we have been letting her fall asleep in our bed (while I do a last bit of work before sleep) but then moving her into her bed. Still, this is getting somewhat tricky as she gets heavier and harder to move without waking up.
The other evening we tried to get her to fall asleep in her own bed, something she has sometimes managed. Unfortunately, she reacted rather badly to this and was getting very, very upset with the idea – trying to crawl over the bars on her bed and begging to be let out – so, in the end, we let her fall asleep in our bed (while my wife and I looked on, as there wasn’t the space for all three of us to lie down). She was resting nicely, almost asleep when she looked up at us, sat up, kissed my wife and said “I’m sorry,” before lying down again and finally falling asleep.
My wife and I looked at each other silently, flabbergasted. Here was a two-year-old with the awareness to know she had behaved inappropriately and the ability to apologise for it even though she’d actually got what she had wanted! This seems to be a level of what could not be called anything else but ethical awareness that is striking at that age, a level which some people never reach. I still feel the buzz seeing her do that made me feel.