You're right. It was Clinton who first used that phrase. I was mistaken.
But as to Reagan's beliefs: As governor of California he signed a very permissive abortion bill. He didn't start pushing a strong anti-abortion stance until later when it became obvious that being anti-abortion was politically advantageous. So I think he might have been closer to "safe, legal, and rare" than you'd like to admit. Certainly he was in favor of safe, legal abortions being available in cases where the life of the mother was in danger, and that's the most obvious example of a "Safe, legal, and rare" abortion. Any interpretation beyond that I'll leave to the analysis presidential scholars.
BTW and just for your enjoyment: