Jerry, yes I did test it and it did not appear to be leaking. I think you may have hit the nail on the head about it being opened when the "plumber" turned on the water. I was there when he did and never saw him go to the water heater until after he turned on the main water. I also remember thinking that it was unusually loud filling up at first then the sound went away (I was by my truck when he turned it on). Now that I think about it, it got quieter when he was walking away. I recommended that they have it serviced just to make sure nothing was wrong.

Thanks!