Am I wrong here?(happened at the park)

Sorry this seems stupid to me so it may seem stupid to others as well. I'm not sure though so I wanted to ask.I'm a stepdad. I was at the park with my stepdaughter today and we were having fun. There was this one kid who was kinda nervous about going from the raised platform onto the monkey bars. After my SD did it I then encouraged this kid a little saying that he could do it. He just had to try. and HE DID IT!!! made it all the way to the end.At the end of his triumph I raised my hand and said "good job, dude! High five!" and instead of high five he said thanks and went for a hug. I was just trying to be nice so i gave him one of those one arm hug/pat on the back.All of sudden his mother and father come up to me and start yelling at me asking what I was doing with their son. I explained the situation and they were still angry and left in a huff.So my question is, did I cross a line? I was just trying to be nice but if I crossed a line I would like to know for future reference. Thanks for any replies! via /r/Parenting http://ift.tt/2zeWOI3