Is it normal my friend treats me like this?

I have known this kid since we were five years old. In elementary school we were really good friends untill about 6th or 7th grade and we started to fight allot, just about stupid stuff and we weren't close again untill senior year in high school (we ended up going to the same high school) and we had some classes together and even had lunch at the same time. As senior year went on he became one of my best friends and we used to hang out all the time and do stuff on the weekends. But once we graduated most of the time during the summer whenever i asked if he wanted to do something he would have some excuse or said he was bussy. But those few times when we did hangout we had a really good time and he would always say how we had to do it more often. He's starting college in about a week and i am in two weeks at different schools. And i really want him to always be my friend. But i wonder if its normal the way he sort of likes our friendship only when it is not a trouble for him.