Why are kids so weird?

Any thoughts on this one: I am a teacher and there is this kid who is in grade 7 who I see at the school. I do not teach him but I know who he is because I have asked him to hold the door for people etc. Anyway, he is from a Somalian background and there is this yellow ticket system where kids who do something good get a yellow ticket and I asked him to hold the door and he asked if he could have a yellow ticket for doing so. I said that he could just this once but if you have to ask for it, then it takes the pleasure out of just being respectful because it is the right thing to do. So I gave him a ticket. Then the next time, I had asked him to hold the door he came back to me at the end of the day and asked for a ticket. I gave him another but said this is the absolute last time. Then he approached me on the school yard and said that his homeroom teacher saw him doing something good but ran out of yellow tickets. So I said that I can't give him one because I have to see him doing something good but that if she needs to borrow some from me then she can come and get them. . .Anyway time ped and then about 3 weeks later, this kid came to me while I was on duty and said, "I have something to tell you". . .He said this very calmly with no facial expression at all. . .then he said, "I really don't like you." And all I said was "okay" and he walked into the school and I guess he was surprised by my lack of reaction that he turned back and said, "I just thought you should know." I was not hurt by that. . .I barely reacted at all but it concerned me greatly that this kid who doesn't even know me can say something this negative without even a wink or a change of voice. . .it was just so calm. . .should I be alarmed? And for those psychology experts, what could this be a sign of? Would there be problems at home with this kid? Will this kid more likely, despite his calm nature, end up being in prison or a psychiatric ward, more so than a kid who does display attitude and show his aggression in a "kids will be kids" sort of way? Any thoughts?