The Good news, the Bad news, and the Good news
The Good News: Despite (unknowingly) walking within a foot of the Copperhead, it did not bite me.
The BAD News: It DID bite my daughter's dog about a minute later - on the bottom of her chin, while Lady was apparently snapping at it.
The GOOD News: Lady has survived just fine.
Only a hard knot at the bite site about 2 hours after the bite that has now softened and the swelling is slowly dissipating under the skin. Without knowing for sure that she was bitten, nothing the vet could do, because anti-venom without an actual bite would not be a good thing. Additionally, Copperheads are the least dangerous of all the poisonous snakes, Lady is young and in good health, and apparently the venom doesn't always effect dogs as it does humans.
24 hours since the bite, she is as frisky and playful as always, eating well, just as ready to come inside and lay in the floor (maybe even more so, after the babying and inside time she got yesterday and last night!)
Lady has come through this a lot better than I probably would have, if the Copperhead had got me instead!