I've found with any phone I've used for the last few years that if I hold it with one hand for long periods of time and I am supporting the weight with basically my pinky (imagine it being in my left hand with my pinky being the only real digit under the phone) then yes, I will get some discomfort or numbness. This is remedied by changing grip and goes away very quickly.

 

I get the same sensation if I hold any phone for an extended period of time. Had the same issue with my S4.

Its a matter of adjusting your hand position periodically.

 

As awesome as the Note 4 is, you should rest your hands once in awhile. I really hope you weren't on your phone 3 weeks straight

 

You know what they say about big phones...