Coolant change, corrosion of res-pump connector

While installing the new monitor wall mounts, I decided to flush the CPU loop on Balthazar because it had become lightly blue again, even after having been flushed 3-4 days ago. I used just a gallon of distilled water this time, no vinegar, and upon checking and cleaning the filter sponge, found the connector fitting that joins the reservoir to the pump was putted and corroded, with the bottom part seemingly snapped off in the top threat of the pump housing. Nothing is leaking yet, and I contacted swiftech for a replacement piece. I'm afraid to check the GPU loop, but the water in there has never had copper sulfate treatment, or turned blue. It still seems crystal clear.