Did the vendor have any other negative reviews for the product in question? It really does seem a suspiciously aggressive response to what should seemingly be a not out of routine happenstance since, as you pointed out, "stuff happens". It could be the vendor has had other bad reviews for products and/or services/responses related to other products they offer through Amazon; maybe there has been a cumulative effect regarding their reviews and they fear Amazon will suspend or drop their seller's account...
It does seem a bit odd; just to be safe, it might be a good idea to avoid buying from that particular vendor...
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