Should be worried about getting swine flu?

I live in St. Louis, Missouri; I heard of two confirmed cases in my state which is Kansas City, Platte County, so, nowhere near where I'm at. Today at work, two of my employees were feeling sick; one of them just had bronchitis and left early. Later on, when I sent the other employee on break she complained that she felt like sh*t, and told me it was probably just her sinuses acting up, and had like this dry cough, and had to use my phone to ask my boss something. She's been covering her mouth, and I've been washing my hands a lot. Should I be worried and could her cough turn into swine flu? I can't afford to get sick or miss work. How long after exposure do you start getting symptoms? Does it come on really suddenly like regular flu?