I've had guy friends and they always send ;) It doesn't mean anything, he was just being himself. Is he typically a flirty kind of person? If so, then it most likely doesn't mean anything, If not, there is still a large chance it didn't mean anything
well sometimes i go " the miami heat are going to win ;D" means like a smiley face with a wink...like.. nevermind, i can't explain it, sorry >.< feel embarrased now..(and yes im leaving it how it is) lol xD
What do you mean "out of no where". This kind of stuff is pretty much common in useless chatting i think. The other person sends you a (; and you send back a :) and everyone's happy while their homeworks remain pending. Don't worry about it!