Greetings! I've read your posts. I hope I'm not leaping into your discussion unwarranted.
I have to agree with everyone's opinion that this gentleman likes you. From what you've said above, I can see some obvious clues. Sometimes even just saying "I'll be up all night!" can be an invitation to spend more time with you.
I used to be a traditionalist when it came to men. I demanded they be the man and ask me out, be the first to kiss, yada yada. Until I met my now husband. Haha. I've been quite the assertive one since day one, and was his first kiss. Sometimes it pays off to be the one to push the envelope.
You say that he doesn't seem the type to be chicken.. but I'm not so sure. I have a former co-worker who is the most sarcastic, teasing, violent guy I know. For the first 2 years of knowing him, I always thought he was pretty seductive when it came to women and very assertive. I've known him 4 years now or so, and was astonished to find out that not only is he extremely shy with women, but was a virgin until just recently. I was shocked. But looking back in retrospect, the sarcasm, the teasing, the show-off attitude is easily a cover up for me. They can act assertive because they have to,but deep inside, they're scared!
Anyway. Yeah... unfortunately with this going away for the summer thing.. it seems like it'll be a while until you talk to him again. But I think when he does get back, it'll open up a big window for you. What if he missed you?