[chirp_users] Permissions for serial device under Linux

I am running Ubuntu 16.04 under crouton on an Asus Flip C302 Chromebook. For the most part this setup works great on most everything except access to the tty device. I have added myself to the dialout group, but I still need to manually do a chmod on /dev/ttyUSB0 in order to avoid the permissions error. It is not a big problem to do this, but I thought that if I were in the dialout group, that would allow me to use the serial port without the chmod. Can anybody tell me what might be going on?

Pat Anderson KD7OAC