1883 Liberty Head Nickels were only minted in Philadelphia. Furthermore, the Denver mint struck its first coins in 1906.
It's great that you noticed this, and it's important to learn from it. Here's the lesson: when you look at a random pattern, your brain is really good at recognizing familiar things in it. Since you're used to seeing D mintmarks, you see one here -- even though the Dahlonega Mint struck its last coin 22 years earlier (and never struck minor coins), and the Denver mint wouldn't open for another 23 years (and didn't strike nickels until 1912). Keep this in mind when you're looking for "errors" or varieties. The more you want to see something, the more likely you are to see it -- whether or not it's "really there".
Numismatic pariodolia - Google it - but as jeffB said your brain is real good at making patterns out of noise... After all some of those patterns were hungry predators wanting to eat you...
Not a D. If you want a mintmarks Liberty Nickel you'll have to get a 1912 as that's the only date with a D.
