Ive been friends with this guy for 4 years and lately when i see him in the hallways hes happy and says hey?

Well chances are he probably is busy. And when he hugs you tight it's probably a friendly gesture. Your friends might hug you really tight when you have been gone for awhile or they have been gone for quite a while too. But he might like you a tint...maybe he just isn't ready for a relationship though and doesn't want to let you know because he thinks you want to get in some type of relationship.