In our dojo during regular classes we do not ask sensei direct questions. Sometimes if the class is small and he looks like he would tell you something I try to get him to explain a few things to me. Usually we learn by observation and constant practice. He wants it this way because the waza we learn, everyone learns it their way. Each with a little bit of flavor to it. Of course it still tastes mostly like senseis or actually a hint of senseis ( because hes too good).
But after class one on one in his office is when I get the chance to really learn the principles or guidelines I try to live by. Usually it has very little to do with technique.
I would like to say that alot of times( the times when sensei is at the other dojos) alot of people ask alot of questions to the more experienced students and mostly the answers are pretty bad(I think). So I do know that the answers arent always right. Actually they rarely are. So unless sensei isnt there I would sujest the questions be kept till later.