Should you salute an officer when in civilian clothes?

If the officer knows you from work, salute YES.

But you MUST maintain your military bearing with Sir/Maam.

no. they don't want it either, just give the greeting of the day, "Morning Sir/Ma'am "

You never go wrong rendering respect to all folks especially if you recognize who they are.

The general policy is if the person is a known officer and outranks you that you should salute regardless of uniform. That is why if at a military entry control point after providing your ID you get saluted. That is the policy you should know and understand. Will any of my peers expect you to salute us in civilian attire, I do not know one that would. To be honest, my biggest hang up is not enlisted that do not salute officers but officers that do not return the sign of respect. I can tell you that if I see a junior officer not return your salute I will crawl up their ass ten times faster than any enlisted that does not salute.