Thanks for the reminder about that. After playing around some more, I figured out what is happening and can reproduce the behavior using the code on the blog:
My code was using 1.570796326794412 for pi/2. This works fine, though perhaps a bit overly precise, for rotating the drawing context in a canvas. However, that many significant figures in the pdf results in unrotated text. You have to reduce the significant figures to the right of the decimal point to 4 or less for g.rotate to work in the the pdf:
g.rotate(-1.5707) // works as expected
g.rotate(-1.57079) // text remains unrotated!
what a weird behavior!