I agree with divine. You don't likely have all the pertinent information, and your role is limited to whether you can give her a ride when she needs one.

In my experience, people who directly depend on business interactions (sales people, real estate agents, business owners, etc.) are often always "on duty" in a way. They are used to wacky schedules, and accommodating client's needs. My brother has been a salesman for much of his life, and he's always ready to go. It seriously doesn't bother him. He loves to work with clients, and while it can interfere at times, he rolls with it and adapts. If the rep couldn't or didn't want to accomodate her on Sunday, he wouldn't. It's probably typical in his work to do this.