Okay to use new KMC master link on old KMC 11spd chain? I took my 11spd KMC bike chain off a few days ago to give it a good cleaning and re-mounted it to the drivetrain using a master link and park tool master link pliers. I must have not set it correctly because as soon as I went for my ride and turned the pedal the chain broke at the master link and I lost one of the pins attached to the master link. 

I removed both pieces of the master link inspected the chain for bent or broken links. It looks good, I had a spare 11spd KMC master link that I fitted in the same spot and road around with no issue. 

Is this something that is okay to do or now that I've had to replace the master link has the integrity of the chain been compromised? 

Thanks!
Many master links from several vendors are specifically designated to be single use meaning you replace it with a new one after you unlock the old one. Which means you'll generally be fine by using a new master link.

For a moderately worn chain, adding a new link to the group of old ones means that less than 1% of your links will be a bit different (a typical geared bike has 110-116 links in a chain). It is unlikely that you will notice it.

If your chain is extremely old and stretched far beyond normal, adding a single shorter link to the mix may become noticeable, at least as a periodic sound appearing when this new link interacts with the rest of the worn drivetrain parts. In the worst case, it won't last because of that mismatch with the rest of the drivetrain.