Whatever the slab it does not appear to me that it was airtight. Toning appears to have environmental issues with it. Nice coin, original grader probably put it in the MS quality area, in my opinion. I love Morgans, thanks for sharing.
MS-64 I don't know slabs very well, so I think I'll pass on guessing. I looks like an older slab though...
I have been on my search for a long nock. And keep finding older slabs and appealing coins that I like.
The 78S has quite a wide spectrum when the TPGs grade them. I have seen many of these with the same amount of contact get into gem slabs, especially with gradeflation. It definitely does have quite a bit more contact than I would like to see in a 64. The exception to this coin is the real nice early luster. Mrs. Liberty has a nice-looking contrast and frost. It just isn't as baggy and choppy as the pics make it. Add in the no line fatty and I just couldn't pass her up.