Not concerning real estate, but property none the less

My husbands exgirlfriend (when they were together) got a settlement and paid off his truck loan and helped pay for another vehicle. Her name is no where on the titles of the two vehicles. To make matters more difficult, I used to work at the financial institute that the loan was at (after the loan was paid is when I started employment there) and on the loan payoff screens, there is no where for the person paying the loan off to put their name as proof of payoff or anything similar to that, and because of the privacy act, the financial institution cannot release anyinfo. to her since she was no where on the account. Now for our question, does she have a case to make us/my husband repay her in court circumstances? We know for a fact she wrote a check for over the loan balance so if she pulled copies the amounts would not match, and does not have anthing in writting or verbal that he would pay her back, she told him to "consider it as her gift to him".
Thank you for your time.

If she said it was a gift then he need not pay back if he does not want to.