she could be just copying, but its not unusual from what i know for dogs to ever use a litter box. I know a few people who have their small dogs litter trained for apartment living.
OK was thinking the same thing, but I have a tendency to second guess my judgment lol...And never knew people litter trained their dogs. I don't have much experience with small breeds unfortunately, but this seems reasonable. Well, I guess she could've picked up a worse habit, like scratching my couches!