Using sudo with pip3?

[jim]

Setting up a new computer to run Ubuntu 16.04. Started using pip3 to 
install all the python stuff I had on the old machine and got this message:

jfb at jims-1604:~$ sudo pip3 install matplotlib
[sudo] password for jfb:
The directory '/home/jfb/.cache/pip/http' or its parent directory is not 
owned by the current user and the cache has been disabled. Please check 
the permissions and owner of that directory. If executing pip with sudo, 
you may want sudo's -H flag.

I (jfb) own the directory in question.

I used sudo because I recall needing to use it on the old machine to get 
something to install. So is it necessary or even desirable to use sudo 
with pip3?

Thanks,  Jim