Print-to-PDF: prevent auto-rotation

I've searched throughout the forum but can't seem to find a clear answer.  I have a .Net application which renders content using GDI+.  Much of the content involves vertical text.  The users of my application print the output to both regular printers and to PDF.  When they print to a regular printer, the output is exactly as expected so that the vertical text is oriented correctly.  However, when they print to PDF, the pages get 'auto-rotated'.  They have to click View...Rotate Clockwise to get the correct orientation.

Is this auto-rotation a recent 'feature' added by Adobe?  Is there a way to turn it off?