Got it figured, so I’m closing this question out.
Here was the problem: on comment approval, I had some custom stuff hooked, and this custom stuff was throwing an error. This error was being included as part of the comment approval’s AJAX response.
It turs out that on listings pages in the admin, if WordPress encounters an unknown AJAX error , it deliberately turns the offending row red. You can see the color being explicitly set in wp-includes/js/wp-lists.dev.js in the function “ajaxDim”.