Some time within the past few years many people stopped answering a friendly "How are you?" with the classic "Fine, and you?", "Not bad", "Quite well, thanks", and the like. Instead, the vast majority nowadays respond with a jarring "I'm good" and variants thereof. Where did this usage come from? By "good", nobody really means that s/he's saintly, or even mildly opposed to evil. And the "I'm good" virus is spreading. Now it's taken to be the civilized way to decline an offer of sugar, wave off a refill to one's teacup, or politely reject a host of similar such small social favors.
Something needs to be done to stop this "I'm good" plague. Instead of propagating idiomatic bad grammar, I suggest we launch a counter-infection: let's start using the archetypal Australian "No worries, mate!"