Motors off versus motors simply not moving?

When I move the motors on the printer I'm building, the power supply fan comes on (presumably because it decides it needs cooling due to the current being drawn). It stays on even when the motors aren't moving. In the smoothie web interface, there is a "motors off" button. If I click it, the power supply fan stops spinning. Is this normal? Is there some state where the drivers are drawing power because they are poised to leap into action even though the motors aren't moving?

steppers are off, or on. On does not mean they are moving. On can be that they are holding position which still uses power.

turning off will result in the machine loosing it position as steppers jump back to strongest pole.

Makes sense, thanks.