That is called a PSA card, in my experience. Among the hundreds, if not thousands, of SGC cards I have had graded from the 1950's and 1960's, I have never had a "loose" card move within the holder, making any kind of sound.|
On the other hand, with a PSA slab, by design and definition, it will move around.
#1 in 1959 Topps. Officially known as Assassin according to stanthemanfan 3/31/2014 and god of minor league basketball according to cammb.