lbb

I'd say it depends on the situation. Did your partner ask you for an explanation? Is this something that your sensei normally expects senior students to do? Are you a senior student?

Also, you may "understand the technique" (or think you do), but you may not understand what your sensei is trying to teach. He/she may be trying to teach a very different application than the one you have in mind, or he/she may be using a teaching progression and not the full technique, or he/she may not be trying to teach "the technique" as such at all but something not technique-specific, such as kokyu. So, again, it all depends on the situation.