Just to clarify; both NGC and PCGS have graded Morgan dollars up to and including grades of MS69. PCGS shows 238 graded in MS68 and higher (2 at MS69) for 1881-S Morgan dollars; NGC's pop report shows a total of 327 graded in grades MS68 and higher (2 at MS69) for 1881-S Morgan dollars. If your point is that TPG's do not grade Morgan dollars at these high grades with the same frequency as ASE's that would be correct. However it is incorrect to say that no major grading service has ever graded a Morgan dollar above the MS67 level.
I do not know the material used but I am fairly certain that it is inert, however like the TPG slabs these are not airtight. I think you are correct that the coin pictured here may have some haze on it, my guess is that came from the environment it has been exposed to at sometime in the past.
To the op @Dejone Maxwell, your GSA CC Morgan looks very nice, better than many of the GSA CC Morgan dollars. From the photos I would grade it as MS64.