Just noticed it's likely less mysterious than I feared: USB activity (moving the mouse or pressing buttons on the keyboard) will wake the laptop up.
I wonder if that was always the case and the impact was lighter before (it went back to sleep faster), or that this wasn't the case before.
Revel in the marvels of the universe. We are a collective of forward-thinking individuals who strive to better ourselves and our surroundings through constant creation. We express ourselves through music, art, games, and writing. We also put great value in play. A warm welcome to any like-minded people who feel these ideals resonate with them.