Rescued A Lovely No-Longer-Dateless Buff! Now, A Problem

So I posted elsewhere that one of my coworkers gave me a pair of buff nickels for Christmas--a 1928 and a dateless. Since I keep white vinegar in the house to clean with and this particular dateless was so worn to begin with, I tossed it in a dish of white vinegar for three days--

--and now have a lovely 1916! The vinegar even brought out a couple of the formerly-lost details in the Indian's hair (no improvement in the buff, although that may be because I had the coin obverse-up the whole time; anybody think I should flip the coin and see if I can bring out the horns?).

However, I think I made a mistake--I used a metal dish, and now, even though the coin has been rinsed in distilled water and is now nesting next to a silica packet to remove whatever moisture I couldn't with a paper towel, there's a little bit of light green under the Indian's nose and around his chin. My first instinct is to say it looks like copper tarnish in appearance, my second is to say it looks like verdigris. Do I need to pick up a bottle of Verdicare, or is this a known problem with the vinegar soak and is there an easy way to get rid of it?