Why will the RP-1 loading for SpaceX's Iridium-1 mission begin at `T -00:70:00` - wouldn't it usually be written as `T -01:10:00`?

$\hspace{6cm}$![screen shot SpaceX's Iridium-1 press kit](https://i.sstatic.net/USkrM.png)

Screen shots (above and below) from: http://www.spacex.com/sites/spacex/files/spacex_iridium1_press_kit.pdf

$\hspace{6cm}$![screen shot SpaceX's Iridium-1 press kit](https://i.sstatic.net/54maf.png)

  [1]: https://i.sstatic.net/USkrM.png
  [2]: https://i.sstatic.net/54maf.png