I couldn't find any episode idea threads, so how about this. This idea is not necessarily intended for a full episode though it possibly could. Some kind of event happens that triggers Yoda to have a flashback, which would go all the way back to when he was a padawan. Maybe he almost had a romantic situation, but resisted. Or maybe something really bad happened and a current situation reminds him of it. Or maybe something from the past that he tried to leave there, has caught up with him.