Ember does not detect Node update

I'm running an Ember project on an Ubuntu 14.04.

Whenever I run commands like sudo ember update, I get this error message :

Future versions of Ember CLI will not support v0.10.25.
Please update to Node 0.12 or io.js.

So I upgraded node to 0.12.6 using nvm.

node -v gives : v0.12.6

nvm ls gives :

-> v0.12.6
system

Is there something wrong with the "system" node? Or a cache I should refresh in Ember?