Well, if Maki's Smile cards in SIF are any indication, this is just how she smiles and shows she's actually happy. That said, sleepy soft Rin is adorable Rin.
@BugDevil "Anne is way, waaay stronger than Grea (thanks to her magic)"
Not true. If Grea goes all out, she's stronger. Besides, her full power has anti-magic attribute, so in an hypothetical fight between the two. Grea would have the advantage.