My house is 30 or 40 years old and I have found 3 pin hole leaks, I guess is how I would put it. One seemed like a fix under the kitchen sink and was almost like a T connection that fed to a hose just laying in the crawl. The second hole also seemed to be a T connection feeding a line that I guess was for an Ice maker line for my fridge. I can come up for reasons why those two exist. Now the third, I discovered yesterday while I was checking on my previous patch. Another pin hole on the hot water line coming from the HWH, I can't figure out how that happened, MY question is whether or not these pin holes just happen or not, and if I am better off getting some copper to pex fittings and switch out all that I can. thanks.