I've discovered that 'why' can often be a very unhelpful question.
Why is she doing this? Obviously, she *wants* to.
The largest difference I've ever dated was a man my father's age (21 years my senior). He turned out to be a psychopath though.
I had no idea what his age was when I met him, and there were definitely sparks.
The worst that could happen is you get a new friend, right? And perhaps she knows someone that would be perfect for you. And perhaps she's simply not an ageist.
Looking forward to hearing how it goes....