The point of bringing all that up is this--one of the big "points" to their training is: Don't try to make these judgments for yourself. Tell the authorities and let THEM figure it out. Better to speak up, and find out it's just a kid with a wild imagination, than to decide not to make anything of it, and find out later you could have done something to help a child avoid more tragic consequences in life.
Whatever it is, I'd tell an authority and let them sort it out.
While nobody wants to do nothing, I'd suggest you have _some_ moral duty to satisfy yourself that there is something to it before involving the authorities.
Unfortunately, the "authorities" have less and less discretion to do the right thing in cases where there is substantial doubt. In some jurisdictions they are required to take certain actions. If in fact, there was nothing to it, the consequences of those actions would then be very unfortunate.
Nobody wants to let something slide. But you also should want very much to make sure you aren't the one to call in the dogs on the McMartins either.
And for the record, every time I hear a cop say "tell it to the judge" I have the same thought... that cop should be arrested on the spot and charged with molesting children, so he can get his turn to "tell it to the judge".
Just consider all the possible explanations, get as much first hand information as possible, and use the absolute best judgement you can muster. And make sure you will sleep well at night if you call it in. Or also if you don't.