Well for me the right weight stabilizer help tremendously with my PSE DNA. I was shooting for an entire year without one but just for fun I installed an old one I had (one of several) that gave me a balanced bow after the shot. In other words kept it vertical.
It made the bow quieter and I shot it better. And the extra weight is inconsequential when hunting from a treestand where I do most of my bow hunting.
But for you, if your group is only 1" larger at 40 yds (and I hope you didn't only shoot one group) then I don't think it would matter if you used one or not.
If you really want to be statistical you should number your arrows say 1 - 5 and shoot these for groups and plot where each arrow hits on a piece of paper each time. You may be surprised at your results. You may have for instance arrow #1 shooting a 1" or 2" group at 40 yards. And the same for any other arrow. But IMO that would be overkill.