This isn't ok behavior. When the firmware updates upon launch the spindle turns on full speed - before the software has even opened. Obviously a huge safety problem.
I'm running a Hitachi VFD using the PWM outputs for speed and two of the relays to control direction. This only happens on firmware update and not on normal launch of the hardware.
EDIT: It does not seem to do it if you have the Estop open but that's not something that should be relied on.