Jadon the Unsociable?

There's two sides to Jadon's interaction amongst people. Towards grown ups, he seems very friendly and sociable. He randomly says 'hi' to people who walk by him and he smiles alot. When it comes to kids his age and younger, he is a scaredy-cat nut case. He avoids them like they have the plague. He doesn't want to be touched and his posture shows it. He will hide behind my leg and if the kid is really friendly and wants to play with Jadon, Jadon begins to cry.

A few days ago a kid, who was a little younger then him, was making friendly overtures and chasing Jadon. He didn't like that and started bawling. The worse thing about it was Jadon looked like he even took a swipe at the kid ( I had to lecture him on that one; I should have put him in time-out but I left him off with a warning). I just hope it's a phase and that he'll grow out of it. I don't want him to grow up being a loner.