Kind of confused to how he hid anything.
Would be better to tell her everything, rather than just specific things. If you were saved by that person, who uses the same power you do, then why wouldn't you tell them you can also use that power. These kind of main characters are honestly annoying. Also, when he told her where he picked up the oopart, that was a quick giveaway he was responsible for the explosion situation. But I do get why he didn't tell a total stranger his power or whatever.
Well, who cares, she was stupid too.