Had a belly button hernia is it cimmon to have a hard mass beneath the belly button nearly a year and a half after surgery?

I would go see : surgeon who performed the repair to see if its just scar tissue and what can be done about it

Probably ok: This is not typical, and is probably due to suture material and/or mesh. Could also represent a recurrent hernia. If it's not botherinng you, it's likely ok, and nothing to do. Best to see your surgeon to check it out. Hope this helps!