Confidence
When Haepha first perceived Jason's aura she already felt suspicious about him, but upon seeing the stigma that glowed faintly, she could hardly contain herself.
Foreign races were able to determine that he was not a pure human right off the bat but it was different for humans to gauge.
They had never seen the unleashed aura from someone belonging to the Celestia race and a stigma of a foreign race in their entire life.
As Jason heard Haepha ask him if he had a trait without showing any signs of noticing that something was off about him, he was sure that he was not in danger.
This didn't mean that Haepha wouldn't kill, attack, or do anything like that to him, which was still a possibility, but he felt relieved to know that even an 'Old one' was unable to tell whether he was a halfling from a foreign race or a human with a unique trait.