Can scar tissue cause chin implant complications 4 years post-op?

Medpor chin implant placed submentally 4 years ago. Localized swelling/soreness just under the incision site since implant was placed. The past couple months the swelling has become more consistent. Swelling/soreness is localized when it occurs and feels like a dull ache/tightness which is aggravated by moving lower lips. Consulted with surgeon who placed the implant, surgeon said it's 'normal' and 'just scar tissue.' Does this sound consistent with normal scar tissue be