No, those were actual ground units the last three times it happened, on the same place: first time a couple GUs, then two times just a single one. And it's on a moon of a planet where i have a huge colony, with 20 deep space tracking stations (with sensors strenght 3000 iirc) covering the entire system waaay outside the jump points. Also there's a pdc there with 1 billion range active sensors, 300m range Res1 sensors, extra thermal and em sensors. There are two entire task forces there too with the same amount of sensors on every ship. And then the civilians too. So I find it really unlikely if not even impossible that even the smallest and most stealthy ship to get that close to my colony totally undetected and drop a few ground units on its moon.
Also that entire race has been wiped long ago, and i re-surveyed all systems and all bodies like 3 times already and none of them have been found, so they have no base to come from in the first place.
