Cam could hear the different, and trace back the reasoning, but she tried to keep her focus on only their conversation. Someone else she might have gone rooting around a bit more but she liked Cas, and not just for that little trick with his tongue.
Do you want to learn more than that or...Just stick with working on singing without letting your emotions trigger others? with a little stretch she looked around the room, just to see if anyone else was watching them. Or rather, watching them more closely than usual. Switching to telepathy meant that their conversation was private, but not everyone would appreciate that.
Always keep an ace in the hole... They had a good idea what Cam could do and what she was seemingly capable of. Cam's plan was to lure them into false security that she was a decent soldier under their control. Useful enough that she could make sure she wasn't kicked out of the program. What Cas decided to do was his own choice. Like Cas, she knew her gifts could be used in bad ways... because she'd used them for that.