The problem is that you misunderstand the question you are asking. When you say "tell me about a time when" you are really saying "Tell me a prepared story abo

The problem is that you misunderstand the question you are asking. When you say "tell me about a time when" you are really saying "Tell me a prepared story about when". In this case the person didn't have a prepared answer for that question so they went with a generic answer to show to you that they knew what they were doing. They could have found & fixed hundreds of bugs in production over their career, but trying to recall an example that will make a good story during an interview is hard and risky. The good news is they will prepare a story for the next interview at a different company.