What an interesting question... (and welcome a-Board, billpy!)
i couldn't find anything (which isn't saying much

) but in my searches i did stumble upon this, which is at least tangentially correlated:
metastasis - casual mention of a subject as if it were unimportant; responding to a person's criticism or insult with a riposte that uses or plays on his or her words (rhetoric term)i thought this was an intriguing twist of the more common meaning of metastasis, which deals with the transfer of cancerous cells to previously healthy sites. it reminds me of a Readers' Digest quote that my mom had displayed above the kitchen sink, where we were all sure to see it often: "Never answer an angry word with an angry word. It's the second one that makes the quarrel"
and BTW, can someone explain what dictionaries mean when they call a term "rhetoric"? are they using rhetoric to indicate that its use would be circumfloribus

?