Good question busting... The way I look at it is, you could go either way. He was not ugly in his comment, he also did not ask for feed back. NC is not suppose to be a lack of any contact, that could be seen as not caring, it's for you and him (mainly you) to have time to heal.
What does your gut say? Could you wait until later tonight or tomorrow to make a decision on answering. If you do reply i like the short and sweet version.
I hope you have a safe trip
You can not change your past, but you can ruin a perfectly good present by worrying about the future.