Good or well?

  Question
A question from a language enthusiast (not at a school!).

When I was 13 (I’m now 76) my then aunty was a senior Catholic nun who taught English literature, grammar and all things associated with English at a private girls’ boarding school in Ballarat East. I recall meeting her and she asked me….”how are you Richard?” to which I responded, “I’m good thanks” and she said “No, you’re well not good” but I don’t recall, precisely the reasoning behind her answer. I seem to recall that “good” somehow relates to my character and “well” relates to my health and that when people ask “how are you” they’re enquiring about your health rather than your character.
 Do you agree that my recall explains the reason why "well/not well" (or something similar) should be the preferred response?
 By the way, whenever I have been asked “how are you?” since that time I have always responded with either “I’m well” or “I’m not well.
Richard

Kate's response
Hello Richard,
Thanks so much for your question!
 I remember too getting into trouble for saying “I’m good” (the reply was usually something like “I know you’re good, but how is your health?). So your recollection that good relates to character and well to health is spot on.
 Sometimes I was also told that “I’m good” is ungrammatical — not that this was ever explained. But in fact, grammatically there’s nothing separating good and well in this context.
 True, in Standard English 'good' is an adjective and 'well' is generally an adverb, but well can also be an adjective when it’s a matter of health, as in something like 'I’m well', and this is because it’s following the linking verb am (a so-called copular verb).
 But there have been changes around these two expressions and the meaning difference between 'I’m well' and 'I’m good' is now more nuanced. 'I’m well' still places more emphasis on a person’s actual health, but 'I’m good' is usually about a person’s general feeling of well-being, perhaps their mood or state of mind (and this is the point Pam Peters makes in her wonderful Australian English Style Guide).'
  And there's a stylistic difference too. 'I'm good' is more informal, which is one of the reasons it’s more frequently encountered these days — it fits in with the greater informality of language generally (and of course, the Australian love of informality).
The changes to this construction have been interesting — go back far enough and you encounter constructions like 'Oh well is me'!