Should I be concerned if I have hardness under belly button incision post gallbladder surgery?

When was surgery? For the first several weeks after surgery there can be some inflammation and "scar tissue" which presents as this. If there is redness increasing pain and/or discharge it may be infected. If it has been years since the surgery you may have a hernia there. Some cancers present as a mass in this area. There are so many things that it could be. You need to see a surgeon for a re-evaluation of this.

Related Questions

Had laproscopic gallbladder surgery; 4 incisions 3 days ago. Dr removed bandages but left gauze & waterproof bandage on belly button. Do I remove?

Double check. If your doctor placed a dressing at that site then they probably want to keep it clean and protected. Double check with your doctor to see how long they want the dressing in place. Usually a few days is all that is necessary. Read more...
Incisions. Generally yes, it would be okay to remove it after 3 days, but not knowing specifically what was done with that incision, i would recommend asking your surgeon. Read more...