Yes, she knew he knew. He always knew. But she said nothing and waited. He did not seem keen on listening to her but then, Issac wasn't exactly her charge. She didn't have control over him and, well, she didn't necessarily want it. "No, I don't feel anything other than irritated," however, 'irritated' was just her natural state of being and had little to do with Issac.
She wasn't at all surprised that they were going unnoticed, assuming that the Mentalist on the floor had something to do with that - putting up a sort of 'don't look at us' shield. They weren't invisible, just... insignificant. "I didn't come here to talk about fish, Issac," though she moved to a tank anyway, watching the creatures swim around.