Why isn't Tatsumaki impressed by Saitama endurance and nonchalance? Should she question herself about his power?

She didn't know about Saitama's true power before this arc and she is clearly going over the avarage against a "mere" A-class hero.

I'm pretty sure she knows no A-class hero is able to keep up with her and should already be damaged or tired, but Saitama clearly isn't and he doesn't even show signs of sweating or panting.

Based on this, Tatsumaki should be wondering how Saitama can withstand her and what kind of power he possess, but she only focus on the combat as if she wasn't rational and fully conscious of her actions, but she stopped for a moment and cleary showed she is controlling herself.

If i were an S-class hero i would be pretty interested in Saitama being able to compete with me with so much nonchalance.