"Don't worry about me... I'll be alright. I'm just going through a phase right now. Everybody goes through phases and all, don't they?" Holden is not going through a phase; any stage of development has a lasting effect on future stages, and is usually incurred by previous experiences. A "phase," by definition, is something passing with no lasting effects.
Holden Caulfield at a young age experienced many troubling things for which he received no moral support. The death of his brother Allie was a serious blow to his psyche, especially in that his parents completely failed at parenting him afterwards, going so far as to let Holden sleep in the garage; if your kid has had something traumatic happen to him, and makes some weird request like wanting to sleep in the garage, you make him sleep in his bed and try to console him to figure out why he would make such a request.
Another traumatic event that Holden had to witness was the suicide of a young boy, who moments before had borrowed his sweater; the boy died with holden's sweater on, even though he didn't know the guy all that well, this one tie brings them closer together and really makes the event strike home. While these are the two major events that seem to have set holden into his current state of mind, it occurs throughout the book that holden will make a casual reference to other troubling matters; unfortunately, because of his way of bringing them up we can't really read much into the particulars, but it seems as if there's more to his fragile conscious in there.
My sister passed through a "phase" in her late high school years. She was one of the greater examples of teenage rebellion, often operating in direct...