Here is what causes the issue:
I connect my external hard-drive (or flash drive) to Ubuntu 13.04. Then using the sidebar from Unity to Right-Click, select safely remove, and then remove the drive. If, after this is done, I select to suspend, the machine will suspend and then after about 3 seconds, wake up as if I pressed the power button to reactivate it.
lsusb shows that the drive has been removed before this happens. System log shows that the machine is behaving as it thinks it should, suspending and then waking up.
How can I check what is causing the "wake" signal? Is there a file that allows me to edit suspend parameters?
Notes from further investigation: Upon reboot, the problem goes away. If I go into the "File Browser" and click the eject button beside the drive, the problem seems to not occur. My thought is it is linked to how Unity is running the "Safely Remove" protocol; but I'm unsure what scripts control that process. Any guide to that would be helpful as well.
EDIT: I attempted to implement this solution by removing /etc/pm/sleep.d/novatel_3g_suspend (I first made a backup in the same folder called ~novatel_3g_suspend); and the problem persists.