I have recently bought a 1998-D Mint Set with some coins that I think are prooflike (all except for the cent, actually). Problem is, I am not sure how PL is determined/graded. The coin in question could reflect about 4" of newsprint that was readable. Here is a pic of the coin (at an angle because direct pics showed no detail, it just looked black) My math puts me at around 52¢ paid for this coin. (the set was $2)
A lot of coins struck after 1985 are struck on burnished planchets and it's not unusual for mint set dies to have been basined. This means the standards of PL are higher for these. While your coin obviously has PL characteristics there is no certainty it will be graded as such.
Also, PL will usually have contrast between the field (mirror like) and the details (frosty or flat).
I think that is really only in the Morgan series and other 19th century classic coins.for example, here is a PL quarter graded as such by NGC from the same era.
This one got a PL designation: http://www.ngccoin.com/certlookup/CertResults.aspx?CertNumber=2580755-047