I don't think it's a case of sixth sense, it's rather just his regualr senses being very acute. I think children, like animals sometimes, can just tell when something's wrong, either by body language, tone of voice, etc. However, it seems to be an ability we lose with age, as people seem to get more and more insensitive as they grow old, and more and more oblivious.

I don't believe in the supernatural, or the divine. I believe in the power of humans, and that we are capable of so much more than it seems like on the suface.