Do you remember checking it for tight fit when you first got it? With me, I'll notice imperfections on every gun I own as the years go by. I never know if they were there originally or if they came through use. I do know that I used to be very paranoid about it in my early years. But then I realized that nothing is perfect and that even if they were, they will show signs of use that do nothing to harm them in terms of function. My guess is that it was probably as loose or almost as loose when you got it, but you didn't really notice it as much because you weren't looking for it. But after you had it for a while, you started to notice imperfections. My MK-40 is not the tightest slide to frame gun in the world (not horrible by any stretch, though). But after many rounds of breaking it in and after one part change (mag catch), it is flawless and is very accurate. And that is what matters most. Took a while, but it proved itself worthy of my trust.
seed.