It always happens, actually -- or has a chance of happening, I should say. The incoming eave notifier only lists the ship that is in the majority in that wave, but the numbers could included a minority of starships or whatever else supporting the wave. On lower diffs, with most ai types, the chance of a starship with a wave is extremely low. That creeps up slightly as the ai progress goes up. One thing to note is that the starships cost unit capacity from the wave -- so if there is a starship, it is in place of a certain number of smaller ships it would have sent.