I'm working on an older 1950's home and was looking to replace a shower diverter (related post of mine: Replacing shower diverter head).
We turned the water off at the shutoff valve, did some work in the downstairs level of the house and then turned the water back on. All seemed good, but an hour later we noticed that in the kitchen on the upper / ground level of the house (which is also level with the shutoff valve), there was water coming from under the sink onto the floor. Note, we did not touch anything with the sink / kitchen area.
It seems to be leaking from the nylon fitting attached to the angles top on the cold side. We shut the angle stop and monitored it for 10 minutes... no leaks, so we believe it was the nylon host that goes to the cold handle in the sink.
What about what we did would cause this? I would like to be able to explain to the homeowner (not my house) why this happened.