Yes, the secret thing would scare me, too. In fact, I have one friend who would not let her child "keep secrets" for fear of the child being taken advantage of by anyone malicious.

I'm guessing in your son's case, that the "secret" is because this was an emotional issue. As we all know, most men and boys (not all) guard their emotions more carefully. Your son felt vulnerable, but what is nice that he entrusted you with this "secret."