I park my vehicle in my garage when I get home from work. 5 hours later, I went to the garage to get something and heard a noise, like something was running. It sounded like the noise was in the area of the fuel tank, like the fuel pump or something under the vehicle was running. After I figured out the general area where the noise was about 4 or so minutes later, it stopped. Any ideas what it may have been? Keys were hanging inside the house and the vehicle had been off for the full time that it was in the garage.