Try
ls -l /usr/local/bin/gfortran
and you may see that it is a link to a directory where you don't have proper permissions.
lrwxr-xr-x 1 root admin 32B Aug 10 18:41 /usr/local/bin/gfortran@ -> /usr/local/gfortran/bin/gfortran
or, even more simply
$ 530: which gfortran
/usr/local/bin/gfortran
It may be as simple as moving /usr/local/gfortran closer to the top of $PATH. I went through something similar in August. Sorry I didn't keep notes, but I don't recall any special trauma.