Initially you know she lights up at seeing Phin cuz wow pretty person who is also helping the warden with his migraine (that even she cant seem to find the cause for) so he must be a Friend! But as with all melusines, I think she def feels something is off about Phin, its just a matter of not knowing /what/ exactly. She's not about to jump to conclusions seeing as Wrio himself trusts Phin to a certain degree.