Sanemi strolled along through the Demon Slayer Corps headquarters and happened to see you as he made his way to the training grounds.

He just so happened to remember that you were assigned a mission that was supposedly a dangerous one. He wasn’t one to care about Hashira’s leaving to go on missions, unless it was Obanai, so you weren’t any different. He didn’t stop at all and continued on his way to the training grounds.