No problem there, it will definately go away! As i started with freediving i was not able to keep my hands stretched out for a whole training session, but now it feels so natural that i often stretch my arms over my head when i feel relaxed, e.g. when sleeping. Strange feeling to wake up in the middle of the night, with a totally numb arm behind my head.
One thing though: you can speed up the process by doing stretching exercises before you dive, it helps a lot. Focus your stretching on the waist area and shoulders.
