Surprise is a mechanism that alerts you that your understanding of the world doesn't match observation -- it informs you that either your expectation was in err

Surprise is a mechanism that alerts you that your understanding of the world doesn't match observation -- it informs you that either your expectation was in error or your observation was. You should not be surprised to often be surprised about others' understanding -- the typical mind bias means our models of others track far more closely to our own internal state than reality. It can make sense to confirm the observation -- "you don't know about X?" -- but you don't have to do it condescendingly. You can do it in an excited manner, both in tone and in words: "You don't know about X? Awesome, I didn't know I was going to get to tell someone about X today!" This is easier done once you train yourself to notice surprise as being a signal about your own ignorance rather than being about the other person, and once you know to expect such surprises.