I assumed the Pisces was not interested....?

Maybe he felt he could express himself better in text rather than talking. I'm that way. If I'm typing something, I can think about it and say exactly what I want to say. Is he shy?

Some men have stupid rules about calling too soon. They think it makes them vulnerable if they look too interested. Did you ask him if he was waiting on christmas or something to call you?

He could be, but Pisces usually don't go that route. He could just be feeling you out, to see how you feel about him and about your date. Have you got plans this weekend? Maybe you could suggest meeting for coffee or something.