history: My dog doesnt bark unless he sees strangers.  My roommate moved out last weekend and lately my dog has been barking/growling at our basement door.  I am the only person living in the house.
current: My roommate recently moved out of my house so now it is just me and my dog.  My dog is really nice and doesn't really bark unless he sees a stranger coming up to the house.  Lately he has been sitting at the top of the steps to the basement and growls/barks.  However, there are no windows to the basement and he wouldnt be able to see into the basement.  I have no idea why he has been barking at that door lately.
next: wow that is a lot to take in.  get a muzzle