He decided it was worth the risk to check on the third man, disguising the casting by incorporating the gesture into a caress on his companions cheek, sending out a questing thought toward that third man with the need to know if the man were indeed a mage Spontaneous Magic (Perceive/Mind - 2/2/1).
What does this spell do? If you are trying to find out if the third person is a caster or not by using a magic, you cannot do that.
Here is a piece of info from the Notes on magic: You remember from the Energy chapter that energy can not be affected by magic in any way. This is the reason for there not being a Base called "Magic" or such like. This also means there is no such thing as perception of pure magic. Identifying someone else as a magician, or determining his energy level, or even just "feeling" magic being cast nearby would require a Perceive/Magic effect, and since the base "Magic" does not exist, there is no way to detect magic with magic.
