She's not sure Shepard got the 'everything's fine' sentiment - or at least, she disregarded it totally, and Tali's not sure she blames her. How often is everything fine with this crew, really? She's definitely not surprised to see the gun, or the generally on-edge air rolling off the commander like a heat wave.

"Maybe I should have just come and found you." And given Shepard less time to build up the paranoia that had settled into her. (And in fact, given Tali less time to pace around and build up her nerves. Everyone wins! Or they would have, if Tali had thought of that before now.)

"I just got my mission reward, that's all." And, because her nerves won't let her keep quiet, "I didn't think they could actually do it, not until Garrus showed us that video he got of what they did for those turians, but...they did something over at Medical."

And then she grins, the smile spreading over her face helplessly as she says it. "I think they might have actually fixed my immune system."