Wake turbulence was my first thought too based on the early report, however, I recall these planes aren’t known for being exceedingly sturdy either.
“however, I recall these planes aren’t known for being exceedingly sturdy either.”
Any aircraft that does low-level terrain following, as the B-2 does, HAS to be sturdy.
in original concept, the B-2 was strictly a high-altitude nuclear bomber. At some point it was decided that it’s operational profile should also include low-level capabilities, which did require structural strengthening.
I don’t know how sturdy these airplanes are, but they are flying wings with no rudder as such, so just a little bit of a tip drag on the ground would produce uncontrollable yaw.