I would argue that in the midst of a period of NC - very occasional, very LIGHT responses are probably good.
I hate to overthink it, but really a hurried civil response would indicate to me that the person was busy, and didn't have time to chat - not a bad impression to give off.
So, let me ask all of the DA club - what are YOU doing to be busy, and not have time to chat? Today I'm snowed in - so I slept in, have been cleaning, watched some TV - really a rather nice day. Spent 1/2 hour composing email to W, but now I'm back on the cleaning rampage.
Work is NOT the best thing to do to fill your time, but I'm setting up for a Super Bowl get together for this weekend! Woot!