PIP Trickery? Assessment in person then week later , a phone call

It sounds as if the woman who called you was just trying yo clarify if you had 'therapy' your condition may improve and you may be able to go out more, therefor this may affect the impact upon your condition and how it affects your ability to meet the descriptors.
It doesn't sound like trickery at all, just an assessor trying to clarify if you meet the criteria for an award and for how long any award could be recommended given that your condition may improve with 'therapy'.