What happens if you need it right now to save your life and you short stroke it in the heat of the moment?
Um, you release the pressure on the trigger, let it reset, and then continue shooting. Even as a died-in-the-wool S&W guy who noticed the longer trigger pull of the LCR right off the bat, I didn't think it was all that difficult to get used to when I shot one. So long as a person practices enough to be familiar with the gun (as you should with any defensive firearm), I very much doubt that short stroking would be an issue.
As to the OP's situation, once the gun is back from Ruger you will have no greater chance of malfunction with it than a brand-new untested gun. Anything man-made can fail and you were simply unfortunate enough to get a gun with a defective part. Once you get the gun back, simply test it for reliability as you should with any new gun before relying on it. If it proves reliable after Ruger fixes it, then don't worry about it any more. The real lesson to be learned here is the importance of thoroughly testing all guns for reliability before depending upon them to defend your life.