since it's a mint set only coin, they probably omitted it. This could be changed if enough collectors demand it. Nice thing about a Dansco album is that you can replace the pages.
They probably forgot. If it's a cardboard coin board, then you couldn't get it in circulation. They also don't have the 1982-plain or other real keys.
I assume it was left out because it was a mint set only issue. I assume it is in the album that includes the proofs (8125?).
I don't think it's in that one either. If they ever did add the space for it I bet the value of the coin would double though (from around $10 to $20).
There's a space for the W dime in the 8125 Dansco w/proofs. Well, at least mine has one. I have the 1996 mint set with that dime and then I bought the W dime again so I could fill the hole.