Yup, I swear that's what happened. I was in the Promenade looking at the stuff the guy was selling (he's the bald, fat guy who sells weapons right next to the painter, right?), and all of a sudden, the Githyanki pop up, start the dialogue and just start fighing. Since my PC had been talking to the seller and was standing right next to him, he ended up getting hit somehow and was toast.
It happened so quickly, I didn't notice it until the fight was over--the rest of my party was on the main ground, not up with my PC, so I had to get them ready with the rest of the Githyanki.