100's of bench presses aren't going to make them go away. Add a little more info (like body type) and you'll get better answers. In most cases (but not all) it's a matter of body fat. A side affect of your 100-125 benchs is you aren't making the pecs larger.
I will agree with sam on this. When I stopped exercising and was eating all sort of junk food I gained a lot of weight. I noticed that my pec muscles lost their shape which gives u tht hanging kind of feeling which we call man boobs. I dont think its abt how much u lift on ur bench. Do u at all do some good cardio? Do 25 min cardio 3-4 times a week after ur exercises. Keep ur bench reps normal maybe 10, then 8 then 6. Most importantly concentrate on ur diet. Find the right mix of protein, fat, carbs etc. If u wanna lose that excess fat the simple theory is to create a calorie deficit but dont starve urself though