Any large-mass landing on a low-G world will kick up some dust.
There was surely millions and billions of microscopic motes of dust,
ionized & levitated by solar UV radiation, drifiting above the asteroid.
Anybody disagree?
As long as Hayabusa opened its sample collection device hatch/door long enough,
it would have collected at least a few nano or picograms worth of asteroid dust.
If it could only return back to earth with it.