An odd question...

Does anyone reading this go through Kendall in the morning? If so, you know those benches, by the steaming globe? When I came out of the T this morning (at around 7:20), one of the benches was covered with paperback books, as if people were supposed to take them. Does anyone know anything about this? Is it an MIT end-of-school-year ritual I just didn't notice before? Or did the book fairy pay a visit to Kendall?