I agree that the CRANKING is abnormal. It almost sounded like your car wasn't going to start for a second. Almost sounded like no fuel?
Anyways, after the engine fired up it seemed totally normal.
Does your engine start (read crank) like that every single time you start it cold? If you can successfully reproduce this scenario repeatedly (BMW is notorious for stating "no problem found"), then I would take it to your local dealer and have them check it out just for good measure.
Hope all is well with your ///M!