I've gotten several of those. And a few shipyard assaults against various empires, where the defenders never showed up.
Admittedly, I'm playing a modded ship so boosted that its stupid (SCS at 450BPV, no shield boosts), but in the NW missions, finding multiple Klingon battleships is still... quite daunting. When it pulls enemies. It should NOT be pulling Q-SHIPS, of ANY size, to attack or defend against it, though. Is that number pushing the scripts out of whack by itself? It should be playable with whatever modding you have in place.