PowerPoint Save As PDF page size 7.67 x 10.17 inches... why?

[ElectroSpud]

In PowerPoint

(Select File)

(Select Save As)

Save As page

(Select PDF)

(Select More options)

Save As dialog box

(Select Options)

Options dialog box

(Select Handouts)

(Select 3 slides per page)

(OK)

(Save)

Saved PDF is generated with page size 7.67 x 10.17 inches

Can't see any place to adjust this. Never asked for it. Don't want it.

Might not have noticed except then I combined the PP PDF with other PDF's to produce a master doc for printing. As you scroll through the combined doc the page size change is quite jarring. What the...?

[#2]

While describing this issue to someone else, I think I may have figured it out. I suspect the size was chosen to be appropriate (i.e. to leave a margin) for printing full-page slides. There was probably no effort made to customize this for different forms of output, e.g. handouts.
As a general observation, I have always wished I had more complete control over the formatting of handouts printed or saved as PDF's. Page size would be a nice place to begin.