Damian might not have any respect for Dick at this point, but he’s still had a revolving door of tutors and mentors throughout his ten years of life, so it’s not that surprising to see Damian retaining something he was taught. He’s an ass, but he’s not an idiot (well that’s also debatable I suppose). I can’t tell if this is some kind of test for Damian, or an actual slip of the tongue. I doubt it’s a slip of the tongue especially since, like I said before, he doesn’t trust Damian yet. It’s a quick way to see if he was actually listening to what he was teaching him.
It also makes me wonder for how long Damian and Dick have been training together before that night. I doubt it was for that long, just enough to have Dick cover the basics, especially since Battle for the Cowl left Gotham in such chaos. Dick probably just covered the basics with Damian, since he knew the kid could already fight.
I hated it so much when Dick first became Batman, but this title quickly grew on me. They were constantly testing and pushing each other, made for some good issues.