Of course he couldn't figure it all out just yet. Certain events in time and space have to happen first. It's just the natural way of things, unless ofcourse she were to come out and just say it. Which, she couldn't, and simply wouldn't do. It would look even more suspicious if she hid her alien heritage, that's why she'd mentioned not being fully human.

"Oh, very interesting 10%." She chuckles and offers up her usual answer. Leaning forward, she whispers in his ear, "Spoilers, sweetie. Besides, you like the mystery of it all. I assure you, I don't have tentacle bits anywhere on me."