That's a term shorter than 1909, before Disney even existed. Seems pretty unlikely. The "life" stuff doesn't make any sense, either; it's always been a genuinely weird term.
In 1909 the US switched from a term of 28 years extensible by 14 if the author lived, to a term of 28 years extensible by 28 if the author lived. It didn't grow to life +50 until 1976.
Edit: I think the confusion may arise from the Berne convention. The US did sign, but not until 1988.
