I had the same question, CGC says the following:
Even though it appears the Eldon collection surfaced in the late '80s, CGC did not officially recognize it as a pedigree until recently. The size of the collection is unknown, but many comics from the '40s have surfaced over the years with the name "Eldon" written on the cover in pen, either printed or in cursive. Subsequent research has revealed that his last name was Hamman, born in 1934 in Iowa, and he served in the Army during the Korean War. He passed away in 1987, likely leading to the sale of his collection. Many rare and key issues were present, including a Captain America Comics #1.
But there are also discussions on the boards that suggest otherwise:
I suppose CGC trumps any discussions, considering they issue the pedigree designations and all...although they're basically saying they don't know either.