Just a few days ago I noticed that our 1-month old indirect hot water heater's pressure release valve has been dripping when we use the washing machine. This isn't just a little drip drip. It's a thin stream of water that comes down for about 30 seconds and then keeps dripping for about a minute. It happens about a minute after the boiler finishes heating up the water in the IWH. Again, it seems to only happen when we use the washing machine; it doesn't occur when we use the dishwasher, shower, or any other hot water faucet.

Any ideas?