Quite often when I am talking over phone with some customer service representative, if they'd need to ask my name again they'd go like
What was your name?
Similarly I heard my teacher asking another student, who was just about to leave the class room, Did you want to stay for another English class? I don't get why is he using past tense to mean if the student wants to stay now or not. In the former situation it sound like if I had changed my name and they are asking what was my old name.
So, why do some native speakers use past tense to mean present tense?