Is hardening under Tummy tuck incision normal?

What you describe is very common. After the initial stages of healing take place, the healing tissue can feel firm or "indurated" for many months.  This typically resolves over time. The area that you describe in the central part of the incision, below the belly button,is the area that is under the most closure tension and has the poorest blood flow. There is a condition called fat necrosis that sometimes develops if the blood flow to the fat below the skin is not adequate.  You are too early in the healing process to make any determinations at this time. I would not worry about it. It sounds like you are healing normally. Gentle massage or a warming pad to the area can increase circulation and is recommended by some surgeons. Discuss this with your surgeon.  Best wishes!

very normal to feel hardness under the incision. this can be a combination of swelling, suture inflammation, or fat necrosis.  usually this will resolve on its own.

It is very common to have the changes you note after a tummy tuck/abdominoplasty. There is often a substantial amount of swelling and firmness in and around the incision site for the first several months after the operation. That said, there maybe areas of fat necrosis in the abdomen as well, but this is quite rare!I suggest that you stay in close contact with your surgeon.I wish you the best.Dr. Gabbay.