Simple question on gasket to a pressure regulator

Folks:

I replaced my home's pressure regulator 10 years ago. Yesterday it started "singing" again. So I went to my local plumbing supply store and bought a replacement. It happens to be a Watts N45B m1. Anyway, got an exact replacement. Removed the old and was installing the new when, because of super close gaps, damaged the o-ring on one side the new regulator. It has a small, removable o-ring on both sides of the regulator so it can be compression fitted/replaced, etc.

So I wasn't down for the weekend, I inspected the previous unit and noticed both gaskets from that one are really good. Supple yet strong and not cracking. So I took one off of that one and put it on the new one. So basically I have a 10-year-old rubber o-ring on one end of the regulator and a brand new o-ring. Keep in mind my last unit was NOT leaking in the slightest. With new and used o-rings on the new regulator, I more carefully installed it and it doesn't leak a drop. All good.

Super, simple question: Should I be worried that the older gasket may eventually fail? I don't mind taking things apart but not sure if I'm just being paranoid or if such gaskets easily can go 10 to 20 years, etc. Not even sure if I can get just a gasket. These regulators are $110 bucks.

 

You already stated it's in good shape and nothing is leaking. The only thing I do with o-rings on my water equipment is coat them with silicone grease to allow them to seal better.