It's the start gcode sequence, it explicitly waits for the bed to heat up before heating the nozzle. The FlashForge factory used RepG to slice those samples and they rigged it to heat both at the same time. You can do the same with Makerware, but you have to work at it because you have to edit the start gcode in a few different places in the profiles, but basically you have to swap the line that sets the nozzle temperature with the line before it that waits for the bed temp.