Thank you, bobc.
I followed your recommendation. I found out that if I print to my PDF (virtual) printer, KiCAD screws up some arcs on the edge cut: it insists on printing the whole circle! However, the preview looks fine. I am not sure if there is something wrong with the PDF virtual printer.
So, I selected print, then selected output to file, and there I had the choice to output in pdf. The output came out as expected. (So, I guess printing to the PDF virtual printer has some quirks, but printing to a file doesn't...) NB. My selection to print one separate file per side is ignored and all comes out in one file. Also, you may want to have both fab layers (top and bottom) turned on from the visibility bar; otherwise you may get a blank output for that side.
The bonus of selecting to print (vs. plotting) is that it gives the option to scale to fit to the page.
Thanks again for the suggestion!