Miss Manners: My neighbor repaid me for a can of tuna I gave her … but it was an inferior brand

DEAR MISS MANNERS: I was active-duty military, eligible to shop in the commissary, where goods were somewhat less expensive than at a civilian market. My pay was also less than the equivalent civilian profession.
A civilian mom who lived upstairs from me once sent her child to ask me for a can of tuna. I supplied them with a can of albacore tuna from a common brand. A few days later, she replaced it with an equal-size can from the same brand, but of lesser quality tuna. The price tag on her can was within a few cents of what I paid for the albacore.
Her action was deliberate. Never again.
GENTLE READER: Your certainty that there was a snub in repaying your kindness with inferior tuna perplexes Miss Manners. Perhaps there is a backstory — or direct evidence — you neglected to mention.
But if you are instead just following the newly popular trend of reading ill will into a casual act, are you not being both unkind and illogical? These days, when people seem eager to scream obscenities at passing strangers, who can believe that anyone would take the trouble to be so subtle with an insult?
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(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, [email protected]; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)