I'm really quite confused... Please help! =/?

So today... I had a party at my house with my friends; Mackenzie, Drew, Faith, Victoria, and Luke. Mackenzie, Drew, Faith, and Victoria all came around 3 so we had a good time playing charades/sitting on each other/ hunt game and going outside to the park and stuff. So we were all laughing and happy when we came back into the house. Then Luke came around 6:35-ish. He's really into Rubik's Cubes and I knew that so I showed him my bro's collection of them (wow my brother's a nerd -.-). Then we went to join everyone else for pizza and ice cream and so i sit on the floor nibbling on food and Luke just comes and sits next to me. He then takes my phone and starts texting his best friend David and then we just hang out. I go to the piano and sit on the bench because I was talking to Victoria, Mackenzie, and Drew who were in that general area. Luke gets up and follows me and sits next to me on the piano bench and starts looking through the sheet music and then starts playing this really pretty piece. He sits on the couch pretending to text David saying bad things about him saying it was from me so i get all flustered and try to get my phone back from him. I end up sitting next to him on the couch and getting off and lunging for the phone, which i didn't get. Finally, Luke gives me a chance and I get it from under his arm. Then we decide to go upstairs into my room and Luke uses the computer and starts making jokes about everyone and when i'm like hey! cuz he was like u guys are so weird he was like not u you're okay(: so then we go downstairs again and decide to play halo. as i'm hooking the xbox up to the tv luke's like i know u like david n i'm like stfu i dont anymore (he knew before i liked david) so yeah then he just gives me this weird look and is like u do i just know and then joins me to find controllers and hook them up to the xbox. we start playing and i kill him a few times with the sword XD (i'm so cheap) and he's like i want a rematch(: so yeah they keep playing and then mackenzie needs to go cuz her ride was there so me and drew went to go say bye to her and when we come back, luke's like i want a rematch! and i'm just laughing but i let faith and victoria play against him while i'm talking to drew (he was in need of some advice). Then Luke's mom and Faith's mom come and we say hi and then my mom starts talking to them so we go back to our game. Luke was like hunting me down particularly to get revenge but i end up killing him again anyways :p so we keep playing games until the moms say it's finally time to go. So I say bye to Luke's mom and my mom's like well say bye to him too so we just look at each other and say "bye" and start laughing. Luke goes first, so i'm just like "bye luke see you later -waves-" and he says bye and waves back with a half smile kind of thing on his face (which is pretty abnormal usually he just nods once at me) and then everyone else leaves. So now I'm just wondering... what do you think is going through his mind? First he's being all super nice to me, then he's accusing me of liking his best friend, then he seems kind of somber to go.