Stranger!!!

So this morning I took the kids to the park and my friend was there with her 4 kids. They were all playing and this guy was playing with what I thought was his son. Then about half an hour later I noticed the guy was still there playing with the kids, but the little boy was gone. I asked my friend, if she knew the guy. She said no, but she had seen him at the park before. He was in his late 20's I would say. Anyway, I asked if he had any kids, and she said no. But she felt a little weird because he was playing with the kids and tickling them the last time they were there. At which point I immediately said, "Okay Kids! Time to go!" The guy came up to us and said to my friend, " You know me, I saw you here once before. My name is Josh, I am a cool guy." He was trying to reassure us. But I felt very uncomfortable and freaked out. As soon I got home I told Justin about the situation and we immediately had a talk with Caroline. Now the kids can't even play in our yard without us there because we live directly across the street from the park. I called the police and told them about the guy and they said I did the right thing and if I ever saw him again to call them so they could question him. This guy was playing with the kids, he made a point to learn all of their names. He was creepy and it ticks me off that this is happening in Rexburg. What better place for criminals to live than this? People leave their doors unlocked and let their kids play outside with no fear... No more... I really don't feel like I am being over protective. An adult man should not be coming to the park to play with children that are not their own. Another suspect thing is that when we left, he left. There were no more kids to play with. He did not seem slow or anything. Was I right???