I have a scab in my belly button & can't rid of it. I had a tummy tuck in 08 & no issues till now. Should I be worried? (Photo)

Any abrupt changes after years of healed wounds requires a visit with the plastic surgeon so they can evaluate the situation.

After 8 years of uneventful post-op abdominoplasty recovery, to suddenly have a non-healing scab means you should see your surgeon. This likely represents a permanent suture that has eroded through the skin surface, and now is bacterially contaminated. This is why it won't heal with local care, antibiotic ointment, or bandaging. The suture must be removed, and this is usually possible via local anesthesia.That should correct the problem. Best wishes! Dr. Tholen

Can't really see based on your picture but it definitely can be a retained suture which is causing the problem.  Not really worrisome but should be evaluated by your surgeon and can usually be removed in the office.