It looks like it might be in a sleeve inside the slab?
I've seen this before with issues that are very small, thin or fragile. The sleeves are used on items like stamps, some Cuban issues, etc. This helps to eliminate the item from shifting and getting stuck between the slab and gasket I would assume. Some gaskets have been custom cut to fit closely around items like diecuts or cut for oddball sizes. It could just be a judgement call.
I could be seeing it totally wrong as well.
