Absolutely, I find that I'm naturally on the inattentive side but hyperactive symptoms present when I'm forcing myself to pay attention to something (like a lecture) and not let my mind wander.
If so, then your inattentiveness could be your mind trying to escape that feeling.
Could it be that you're dreading something that is "implied" by the lecture in a way? Maybe the practise that you feel obliged to do? Maybe the impact the lecture could have on your work or schedule? Maybe just the end of the lecture and back to whatever comes after?