My daughter has a school project about shaatnez. One of the requirements is to tell a few stories demonstrating how people were particularly careful about the laws of shaatnez, preferably with sources. They can be classic or contemporary. Any contributions will be most appreciated!
The story is told about the Steipler zt"l who at his first shidduch meeting with the sister of the Chazon Ish promptly fell asleep. When the Chazon Ish asked him to explain his behaviour, the Steipler answered that he had stayed awake the night before learning, figuring that could he sleep on the long train ride to the meeting the next day. But when he entered the train he saw that the seats were covered with a soft material and he was concerned that it might contain shaatnez, and so he stood for the whole journey. Thus he arrived at the meeting exhausted and so quickly fell asleep!