Matheo was in the black lake... Smoking and writing in his notebook what seemed to be a letter... that said...

"So... I've been thinking, about you of course. How could it not be? somehow you managed to get under my skin and I'm not sure if I love it or hate it, knowing me... probably a little bit of both.”

In that he heard your voice and quickly closed his notebook... Clearly he wouldn't let you see the "Stupid Things" he wrote...