Don’t you just hate it when your Business Analysts (or others) beat you to it and point out bugs before you have a chance to?
It feels so unfair! They can send an email that says, “the columns aren’t in the right order, please fix it” and the programmers snap to attention like good little soldiers. Whereas, you saw the same problem but you are investigating further and confirming your findings with multiple oracles.
Well, this is not a bug race. There is no “my bug”. If someone else on your team is reporting problems, this helps you. And it certainly helps the team. You may want to observe the types of things these non-testers report and adjust your testing to target other testing.
But try to convert your frustration to admiration. Tell them “nice catch” and “thanks for the help”. Encourage more of the same.