Weird occurance today

    A minor thing yet strange nonetheless. I was walking the dogs today at about 4pm and as we were returning to the house I noticed the evening paper on the front stoop. So the dogs and I went over to the front stoop to get the paper. Just as I was picking it up the front door shook like someone was unlocking it to come out. Figuring my wife was coming out to get the paper, I waited. No one appeared and the door did not open. Our front door is extremely heavy, made of local walnut. Wind, which was very light, would not have moved that door. The parlour door is kept closed as are the upstairs bedroom doors that open onto the front hall and staircase so it wasn't suction from some door being opened in another part of the house. My wife, who is suffering from a sprain isn't moving about a whole lot anyway. When I reentered  the house through the side door into the kitchen my wife was standing at the sink. I ask if she had gone through the house for the paper. She assured me that she hadn't left the kitchen. So what made like it was coming through the front door? I haven't figured a logical explaination as yet. If I do I will post it.