We have a daylight basement...meaning it is underground on three sides and opens to outside on ones side. We have two sets of french doors down there...as well as our laundry room, extra bedroom, game rooms, storage, etc. We have no door leading down to it...just an open stairwell, since it is part of our living space (heated, cooled, finished, etc).
Sometimes, Mojo and Lily will stand at the top of the stairs...looking down and whining or barking. We never had problems with mice...... but when we had our pest control people out for our yearly inspection...they found signs of a mouse
So, I am thinking that is what it was!!!
Whatever it was....they most have taken care of the problem because Mojo and LG don't do that anymore! Whew!
So.....I hope it is just a mice that can easily be taken care of!