Suspicious PCGS Slab For 1911-D Half Eagle?

I looked at this coin on ebay and thought I might place a bid. However, I checked the slab number on the PCGS website and got an error message "this cert is not available for display". I've never seen that for any other PCGS cert number that I checked. Does that mean the slab is a counterfeit? The label color looks off as well although that could just be a photo issue.

The coin went for $817 which is a decent price for a genuine PCGS-slabbed AU-50. Did the buyer get a bargain or were they the victim of a fraud? What are your thoughts?

Here is the ebay item number: 270871358264

I could not post the direct link to the listing because my antivirus program detected a Trojan virus problem in the link. That's something else I have not seen before.