I have four active road bikes. Recently, at essentially the same time (within a week or so), I experienced them all suddenly producing a "creaking" and/or slight clunking sound from their cassette BBs. Further inspection indicated that they all needed to be snugged up and tightened just a bit. I DON'T live alone...but none of the others in the house would know a BB from presta valve...nor even where to find my tools to loosen them.
But...most of the planets of our solar system are on the same side of the Sun. So I'm thinking cosmic forces are at play.
Dan