Update:

I parked at the Millbrae Bart station Saturday morning and retrieved my car mid-day on Monday. No problems.

Next time I am parking on Friday and pulling out Monday morning, and hopefully that will be OK too.

If I had known this earlier this year, I would have saved a lot of $$ in airport parking when time was tight, and a lot of time when I was trying to use the free parking at the Atherton Caltrain station.
But I guess better late than never!