Now, I don't know what he was thinking, but I feel like I can relate to that delayed response. It happens to me when I don't grasp what the other person meant and am processing their words/actions, when I'm caught off guard/bothered and enter "bracing myself mode," or when I'm trying to formulate what to say or do in response. It's expressed as:
Looking and blinking at them.
Watching the moment pass by and standing there while I wonder what just happened.
And that's not a bad thing :) While I may feel lost and awkward quite often, I've learned to respond in my own pace and style. I've learned that when I can't speak the language, I can still speak with a smile. So I watch this brief interaction in the movie and feel both amused and "in tune". hehe thank you, Mr. Spock!