Leaking tee fitting.
The tee crimp ring had split causing a leak behind the laundry tub.
This leak had caused a lot of water damage to the gib behind the laundry tub. After cutting a hole in the gib behind the tub to investigate. I finally traced the leak back to the ceiling void. The crimp ring has split, possibly due to expansion and contraction over the years. The water had tracked down the hot pipe and continued to drip from the wing back fixing.
If you have any signs of water damage give me a call. Meeting your plumbing needs.