First of all, I am surprised that the examiner did such a quick throttle roll back. The FAA has issued notices to Examiners and CFIs about this, as there are some helicopters that could under certain conditions have an actual engine shutdown because of this action.
As for FAA Inspectors, on the helicopter side for the most part, they are usually quite experienced. But you do find a few that are not. Then the checkride could get quite interesting. Fortunately, the ones I have dealt with have been quite experienced.
Which redline did you go over? The engine or rotor? If you are in autorotation with the needles split, the rotor RPM can go over the engine redline, just as long as you do not go over the rotor redline. I do know of one inspector that insisted that you could not go over the engine redline. His reason was that the engine was still running.
I would not be concerned about this checkride. No one really cares when it comes down to it. And they will never ask. Do you ask your Lawyer how many times he had to take the Bar Exam? Of course not.