I think people are blowing it way out of proportion...the kid is what, 18? He scores his first goal, jumps on Maxwell cuz he's absolutely going ape shit, celebrates with the team then runs over to his best friend on the bench. What is so wrong with that? I love Messi, he's my favorite player in the world right now, but he's no "god" to worship. Messi has always been very humble and I'm sure didn't care; if you watch the footage he actually turned around and started jogging back right away instead of celebrating. IMO he was a little frustrated he couldn't score and wasn't really in the mood since he was resting for the CL.
FYI- Messi has gotten a lot of opportunities from other players, especially from Zlatan. It just looks like he has to do it himself sometimes- and thats only b/c he's good enough that he can