Board Thread:Episode Discussions/@comment-27924662-20170419222535/@comment-25122992-20170422161624

Well, and why should he notice? All the scenes show that the doujutsu reacted on the dark chakra automatically, without Boruto even knowing it, the only thing he noticed that his sight has shown him something unusual. Also, it's not like he's completely unaware about its existence since he bothered to ask Hinata about her Byakugan.