When you cast a concentration spell, ending the last spell you were concentrating on.
(comicpress.socksandpuppets.com)
From her goblin clan originally.
She's just had a lot of high level healing magic applied to her during her adventuring ties, so little nips like that tend to heal out. (The DMG actually has some guidelines for what levels of magic can heal various forms of minor permanent marks like scarring etc - it's interesting)