When Leonard comes in blowing his nose and asking about his inhaler, Penny turns around, supposedly disgusted or annoyed, but it can be seen a glimpse of Kaley Cuoco trying not to burst in laughter (half covered by her hair). The following scene, she's clearly bothered.
Sheldon gets his story about the king wrong - the point of Attar of Nishapur's fable is that the wise men were supposed to come up with something that would make the king not only happy when he was sad but also sad when he was happy, and "This too shall pass" is always appropriate.