Generated PDF is off center

**Expected behavior:**
Once an icon is approved and `grunt` has been executed, the generated pdf file should be centered

**Actual behavior:**
The generated pdf is off-center. As a reference these two pdf were recently auto-generated:

[trending icon](https://github.com/Automattic/gridicons/blob/master/pdf/gridicons-trending.pdf)

[recent icon](https://github.com/Automattic/gridicons/blob/master/pdf/gridicons-recent.pdf)

Start with the grunt task that runs after an icon is approved and compare its generated output with the linked trending and recent PDFs. Trace the PDF-generation step and verify that a regenerated icon PDF is centered, using those references to confirm the result.

Written by the indexing model from the issue text.