I really hope that she contacted you (via note or something) and asked permission for that use so that this is all just a big misunderstanding... but because of the lack of a nice credit I highly doubt that that situation is what happened..
I hope this doesn't ruin your day.... here have a hug to make it better.
Ah, she is beautiful, LadyAmaltea :3 I see you decided to take a small break from ponies in LU style and try something close to the MLP:FiM style, just in your own interpretation? Can't say I'm disappointed, heh. Any plans to draw her fullbody? I really like how elegant and graceful your ponies are, I bet the Princess would look gorgeous in your "style" :3