Unfortunately Tim doesnt (from what I remember reading) go into this in the book..which I would say is kind of irresponsible.
When you raise your testosterone level, it also increases your estrogen level. Increased estrogen level in men can lead to gyno. The best way that I've heard to help with this is to take 50mg of zinc picolinate 2 times a day (for a total of 100mg a day..maybe 50 when you wake up and 50 right before bed). I've heard of body builders who are on roids taking even more, but generally I see peopel recommending 50-100mg a day. Zinc acts as an aromatase inhibitor, which inhibits the enzym that converts your testosterone into estrogen. This will help keep estrogen in check.
But honestly, unless you've been tested and your test level is below average i think its kind of dangerous to mess with you hormones for no good reason. A lot of them are sort of interconnected and when you mess with one, a bunch of other things get fucked up.
As far as the tissue going away, I've heard in some people it might go away on its own, but more often than not it would take surgery to remove if it really bothers you.