On the third day after mine was born, DH was holding him a few feet away from me, and I waved at him. He waved back, and I was convinced it was deliberate. Only happened that once though, so I suppose it must have been coincidence. Still...
Similarly, days to weeks old, DS5 would pout on queue. Pouty Face became part of his nickname.
And looking back at another thing. I can remember at DS5's 24 mos well check appt, our pedi asking about how many words were in his vocabulary. She wanted to make sure he had at least 20-30 or something similar. And when I said he had at least 200 or so, she reacted in a way I should've picked up on. It wasn't that she was shocked, but it was more of a "I knew this kid isn't average".