Your incisions will go through a maturation #process after gynecomastia surgery. For the first few months they will be red and possibly raised and/or firm. As the scar matures, after 6-12 months, it becomes soft, pale, flat, and much less noticeable. You may experience numbness, tingling, burning, “crawling”, or other peculiar sensations around the surgical area. This is a result of the #healing of tiny fibers which are trapped in the incision site. These symptoms will disappear. Some people are prone to keloids, which is an abnormal scar that becomes prominent. If you or a blood relative has a tendency to keloid formation, please inform the doctor.
Also, as you heal, the area may feel “lumpy” and irregular. This, too, decreases with time, and massaging these areas will help soften the scar tissue. The #compression garment helps reduce the swelling, and the longer it is worn, the more quickly you will #heal. It can also assist in the retraction of the skin. If you have any concerns about #healing, its best to ask questions of your surgeon or their nursing staff. It's possible the indentations can be addressed with cosmetic filler(s) if eligible.
i cannot tell at all what it could be by your description. Please attach photos from front, side and angle.
Concavity over the lateral mid breast is common and can be corrected by filling with fat transfer; you have to make sure that the surrounding area does not to be brought down at the same time. A photo would be very helpful to give you a definitive diagnosis.