Could a scar from a hernia op still be painful ?

It depends: How much time has passed since surgery. All operations take time to heal. If pain persists more than a few weeks, consult the surgeon who performed the operation.

Maybe: It depends on where the hernia location was, the technique used, and other patient specific factors, most important of which is pain before the operation. Pain usually resolves by 6-12 weeks, but it is normal to have occasional, mild, fleeting pain for years. If you're concerned, call your surgeon for a flow up appointment. Hope this helps!