He doesn't even skip a beat in answering her question. Doesn't even ask how she guesses what 'spatial-timeline fuckery' means. So either he's guessed that she's a scientist (probably not likely, it's not as if she's asked anything that's particularly science-y) or that she has experience with people with powers. The latter seems most likely.

Caitlin raises an eyebrow. "How old does he look, and how old is he really?" And how did it happen, she wonders silently.