I leased a TB mare that turned out to be stolen and had to give her back. Found out by reading the lip tattoo and checking it out. By doing some lengthy backtracking, we found out she'd been through at least 4 different people after she was stolen. She'd been missing for almost 3 yrs. I never ever take a horse onto my property without a bill of sale. Too risky. You could be held accountable is someone comes looking, even if you did nothing wrong. If you have a stolen horse, without a bill of sale, you have no proof that you weren't the one who did the stealing. And you're right, the lady does seem to be acting suspiciously if what you say of the conversation is true.
"Keep a leg on each side and your mind in the middle"