No longer quiet

Today is the first day that sounds are again be heard in this house. Frankly the extreme quiet was getting to me. It started this morning. My wife left for the store. Shadow (my surviving schnauzer) and I planned on picking up the mail and joining my wife at the store just before noon. I was reading my computer mail and everything up to that point was quiet. I distinctly heard footsteps coming through the kitchen but ending at the foot of the rear stairway. Shadow was laying on a cushion in the Dining room and I heard nothing out of her. Normally any stranger would put her into hysterics. I am in the library at the computer, just off the dining room. Nothing more was heard and either the intruder was recognized by Shadow or it was simply a sound that is common to her. I suppose I should have gone to see if anyone was there. But I didn't. I hadn't heard the west side kitchen door open nor heard the bell that rings when that door is opened. So, being busy (actually lazy) I didn't investigate. Until recently foot steps being heard in this house is not that unusual. I did note the steps sounded like hard leather shoes on a wood floor. Our kitchen has carpet. The weather has gone from cold, upper 20's daytime, around 0 at night, to 40 daytime and 34 at night. Temperature swings, I'm told, can cause noises in old houses, by I cannot figure out how the trailing sound of footsteps could be thus produced. We had 5 inches of snow, but almost all of it has melted in the higher temperatures.