Later: No magnitude yet, but it was close, on the San Andreas about ten minutes from here.
And: it was a 4.3 -- felt stronger because it was close and shallow.
Now to decide if I want to go up to the loft as I usually do for lunch. I work in a three story unreinforced cinderblock warehouse, and if this was a foreshock, I don't want to be upstairs with no protection.