It depends on where it hurts. You have little muscles around your sit bones. They might hurt after a ride if you haven't ridden lately or if the saddle is new. Those muscles toughen up fairly quickly.

If your gluteus maximus muscles hurt, that means you got good exercise.

If the saddle hurts around your pubic bone, it might be because the saddle is wrong for you or because it's not adjusted right. Your saddle should be level or very, very slightly higher at the nose. It should not point down (lower at the nose).