I'm thinking I had some bizarre odometer/date coincidence, like hitting 99,999 miles on 9/9/99. Funny I'd forgotten about that.
I've heard that the desire for symmetry is a sign of a cluttered mind. I definitely like symmetry but I don't think my mind is exactly cluttered. It is much like my home though, lots and lots of STUFF from all over; some things interesting and useful and some just fluff or plain difficult to part with, but all pretty well organized and accessible.
So do all you folks with these idiosyncracies share their existence with others, or do you keep in under wraps as best you can? I got to "come out of the closet" as it were when I worked with autistic people. At last, others who understood that having the floor mat in the car lined up exactly parallel to the side of the car is preferable to having it carelessly askew. I relish my little quirks. When I bought my first house, the owner explained that some of the doorknobs might be a little loose because he always gave them an extra jiggle to make sure the door was locked. I could relate as I am a long time world champion door knob loosener. I also used to turn off the bathtub faucet so tightly I needed a pipe wrench to turn it on again.
Our animals are creatures of habit as well, so the desire for routine many of us have complements the care they need.