New needle or cartridge

I got the new needle for my Ortofon 2M bronze last week and today I've been playing some Vinyl and for some reason it sounds better but I can't pinpoint what. This maybe down to the old one was on it's way out but I'm leaning more towards that there is a difference. If this is right and I'm not imagining things it's good news as it's not worn in yet. It's doing my head in why?!!!

The thing is I had look at the old one close up and there didn't seem much wrong with it. I have heard that some manufactures do refine their carts over time or at less make better manufacturing processes, I'm not saying Ortofon as done this with the bronze but being an ex engineer you are given a tolerance of plus or minus and maybe I've got one nearer to spot on. I'm happy no matter what.

The trouble I have is I don't know the amount of playing hrs that was on it and I can't even remember when I bought it. As for the set up I do know that this is not the same as I started from scratch, I thought it was a good time to give the turntable a good clean before fitting the new needle. Under the microscope it did show up some dirt which I was surprised to see. I doubt I'll try to see if the old needle is any good as I will use the old adage "if it ain't broke don't fix it" and looking into see if the old one is OK will eat into my record playing and listening time.