I'm newbie and recently bought phantom 3 pro. One thing that makes me wonder is that almost always when I want to start the motors I need to spin one or more propeller and only after that it starts when using auto takeoff or CSC. Is it normal ?

No that's not normal ( well never heard it before ).. Can you post a video of the issue?

Remember to buy extra propellers and one or two spare batteries to keep you flying

www.Phantom-Guide.co.uk - The Ultimate Phantom 3 Resource

Not to make lite of a malfunctioning P3. Still got all your fingers? Sorry could not resist.  You definitely have a problem. Return it.  

Be sure to yell "clear!" before spinning the props!

Just kidding. That doesn't sound right and doesn't sound good.

Make sure you didn't put prop guards on this and over tighten the screws! That could possibly bind a motor.

Prop guards?