Finally saw episode 5, and wow Teresa was awesome...kicking an abused little girl in the face with no remorse whatsoever, that's was frigid on a whole new level.

Anyway I don't think it was ever mentioned that this was a flashback in the anime at least. When the little girls name was revealed I figured this was either a flashback or Teresa knew our Clare already and was somehow reminded of her by this new little girl. While her face looks similar in profile, Little Clare's hair and eye color don't match big Clare's when she's on those normalcy pills so I was a little skeptical. If it does turn out to be a flashback I think that might end up just being a plot hole.