A strip in the Execution comic made me remember that women aren't believed to have the Stalker Senses™ that men have.
But in Execution, Sergei claims that Sanya is way more capable of becoming a Stalker than he is when he first started out.
(This bit also interested me, is this Nikita being misogynous or genuinely not wanting Sanya to go because he cares for her?)
Is it because she's a mutant and can naturally sense anomalous objects? Or does she actually have the Talent?
And if she DOES have the Talent, why couldn't she sense Katya's mutation? Is it because she's a mutant herself and is constantly sensing her own mutation, growing accustomed to it and tuning it out?
I find it interesting how Ferry decided to put this dialogue in the comic, so it's all just speculation for now until she says something about it.