[The slip triggers some alarm in Garak's mind. He may not know Data well, but he has an eye for patterns -- very important for a tailor (not to mention a spy) -- and this is a jarring deviation. It shows only in a slight narrowing of his eyes -- his tone remains as friendly and condescending as before.]
Yes. It's always surprised me that humans have known Vulcans for so long, and yet have completely failed to adopt any of their habits.