Your body normally generates 20ml of cerebrospinal fluid an hour. I doubt all that can come out of your nose. If your CSF had run dry, you'd be a lot lot lot more sick than you currently are, so don't worry...
Perhaps the spinal tap took 40 minutes because they had difficulty accessing the right area to tap on your back? It happens...
And why are you asking here instead of going to your Doctor? Seriously, go to your Doctor or a specialist.