Gervais like levels of embarassment

Some conversations you shouldn't have where someone can overhear part of the conversation and possibly not get the context.

Yesterday, I was talking with some friends and the discussion got around to people who have said things that may or may not have been discriminatory against one minority or another but got in trouble (or in the case of politicians, had to resign) because they sounded like it. I told the anecdote of a man who nearly lost his job for shouting at a cat - the cat was black, and the man, having found the cat using his hat as a kitty litter, shouted a three word phrase of abuse at the cat that included its colour. The question was, was the man racist for using the colour of the cat in his otherwise generic abuse (he also questioned the likelihood of the cat's parents being married, which on the face of it is probably an accurate reflection of the situation), or is it quite possible for someone to view cats as not deserving of respect but automatically give it to all humans? The problem was - someone heard me say the phrase the man used and thought I was telling a racist joke - I know this because he threatened me before leaving.

So then this sparked off my levels of angst worthy of one of Ricky Gervais' tactless characters - does my telling this anecdote mean that I am also racist, and hadn't realised? Should I have been as unable to bring myself to use the phrase used in the anecdote as I am unable to say out the full name of the hip-hop group NWA? Or am I just tactless, thoughtless and socially inept (which I pretty much knew anyway)

The man in the anecdote, by the way, wasn't sacked, but had to attend sensitivity training. Perhaps I ought to do the same.