Is it safe to use the washer if the hot water supply hasn't been used in two weeks?

You should take precautions before using the washer if hot water has not been used for two weeks or more, as hydrogen gas can build up in the water heater and may be explosive. Turn on all hot water faucets and allow them to run for several minutes before using any electrical appliance connected to the hot water system to allow any built-up hydrogen gas to escape. Since the gas is flammable, do not smoke or use an open flame during this process. (Page 3)