She wants to be your source! Working by referral gives her an opportunity to be the best she can be and provide you with exceptional "giving" service. She wants your future referrals and knows she won't get it if she doesn't go "above and beyond" the competition.
After all, buying or selling real estate is not just a transaction. It's a lifestyle change, full of emotion and it's about building relationships that are going to last. She's going to be available to you long after the closing to meet ANY needs you have. Ask her about joining her Client Appreciation Program.