No I had, but just always took the saying literally.
“Many moons ago, I had a car.” Could’ve been last week.
“Many moons ago, I was in diapers.” Was definitely not last week.
Months are literally based on the phases of the moon. The word "month" derives from "moon" in every language I'm aware of. If you took it literally, you'd understand that "moons" is analogous to "months."