This is incorrect. Any matter within about three Schwarzschild radii will never escape the black hole - i.e. will be carried along with it - even if the black hole passes you at the speed of light.

And if the black hole passes you at a velocity lower than the speed of light, then the radius grows. That matter will begin orbiting the black hole and will leave your body just as fast as the black hole left.

What's the Schwarzschild radius of a black hole the size of an atom? Or would something that size evaporate before it got a chance to snatch any of my leg?

The whole idea of encompassing an object that warps space into a sphere in our unwarped space is just a little invalid, especially when examining them on the scale of their constituent particles. I really don't know the answer, but I do not think that a black hole could be the size of an atom. I would expect the strong (or was it weak) nuclear force to overcome the mutual gravity and so compact an object would not be able to form.

I'm just a layman on the topic, and would greatly appreciate any insights by physicists in audience.