Do Japanese people not seat unless offered a seat?

in the Japanese courses I am taking, they some times bring Japanese people to visit as part of their program working with the embassy. Some times the visits are short some times they are long. The thing is that I have noticed in the long visits is that they never take a seat, and the classes are 4 hour long. In our culture you do not need to be granted permission to seat, you just do. I am wondering if this is a cultural thing that I may bring up to my local born teacher that may be unaware. Because I kind of see them struggle with standing up, and I want to do something about it.

by undostrescuatro