Will He Call?

I just returned from a week long trip to California a couple of days ago. I went with a friend of mine and we became pretty close, being joined at the hip and all. But now that we're back to our normal lives, I haven't seen him or talked to him. Both of us did say that we feel we've gained a good friend in one another, and he did say that he would call me, but there's a part of me that thinks he won't. Now, don't get me wrong, this has nothing to do with anything romantic. This is completely platonic. But I have grown to care for him very much and I value his friendship. I'm just at a loss as to where it's going to go from here. In all honesty, I'd be more surprised if our friendship ended up growing and becoming stronger than if not, and that has nothing to do with him. He's never given me a reason to think this, but it seems experience would dictate that we won't end up spending much time together, we'll drift apart, and the only thread we'll ever have is the trip. That is somewhat disturbing to me. What has happened that makes me assume the worst instead of the best? I'm not saying I don't have good, close friendships. I guess I'm just lamenting over the fact that my natural response to this situation is to expect our friendship to fizzle out and die instead of grow stronger, and that I don't think I'm totally unjustified feeling that. I would really like to see us become close friends though. I guess we'll see how it goes. Worse case scenario, I could always pick up the phone and give him a call :)