So maybe Mars isn’t as inert as we’ve come to believe: Mystery Mars haze baffles scientists.
Would be interesting if this was a dust plume kicked up by a small asteroid impact. On the other hand, I’d think if it had been, someone would already have teased evidence of this out of the rover data covering the period in question, if either of them carry sensors sensitive enough to register the faint effects of a rather distant seismic event or transient pressure/acoustic pulse in the thin atmosphere.