I taste mold in the water from only one faucet inside my home---bathrooom. The taste seems to occur from water that flows from it after the faucet has been setting for several hours of non-use. Once the water flows for several minutes and the faucet is used many consecutive times within an hour, the taste subsides, but then returns after the faucet sets again with non-use for several hours. Can mold be growing inside the pipe causing this problem? No other faucet in the home has this moldy taste. This problem just started over the last year. I have lived in the house for over two years, and the house is 56 years old in Austin, Texas (pier and beam). I did have to have some mold cleaned from one of the bedrooms in the home two years ago.

could be the pipe is contaminated with bacteria. and might spread to more of the pipes. strange one.
if you have a filter on the house ,you can remove the filter and fil it with bleach without the filter and run each tap until the bleach smell comes out then turn it off and do each tap including flush the toilet. let sit for 3 hours minimum and then open all taps to flush bleach from system.. this should clean any bacteria from the pipes.