Inside of the connector that plugs into the bulkhead looks like it got hot. Still plugs in fine and contacts are okay as far as I can tell but at the bottom of the plug it is rough as if melted a tiny bit and I was able to pick off a couple small pieces of plastic that might have come loose as if melted of a small layer. Didn't pay much attention when cleaning the connector but now I recall seeing it. Again, everything plugs back fine and metal contacts are firm and in place. Any idea what happened and what I should do now?