It's probably something bullshit to fight off lawsuits - "the computer says you weren't hopping on one leg, dancing and throwing salt over your shoulder, and you didn't activate car wash mode, we can't help you sowwyyyyy". Manufacturers don't want to fix on warranty after all.

unless there’s some sort of extreme panel gap that let water in and caused a short or something.

Coincidentally, poor fit and finish is a common complaint among Tesla owners.