I feel bad if the offense was one based on indifference or arrogance on my part. But when the offense is simply based on an expectation of others that one does not hold themselves to, screw the offended. Most, if not all people, are subject to blunders. Let it go and keep corrective comments checked to the level of politeness. High hat corrections from anyone will get spit from me in return. Want to show they are a dick or an ass- all they need to is open their mouth and move their lips. There is a way to correct people who blunder across the lines. Unfortunately, it is a skill not learned or practiced much of the time.