Per Make apt-get (or aptitude) run with -y but not prompt for replacement of configuration files?

I did the following:

ec2run ami-3c994355 --region us-east-1 -n 1 -t m1.large -z us-east-1d

On the machine:

sudo apt-get update
sudo apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" dist-upgrade

I still get a prompt asking me which config file I want to use. These are the lines that come before the prompt:

Setting up grub-pc (1.99-21ubuntu3.1) ...

then:

                         +-------------------------------------------------------¦ Configuring grub-pc +-------------------------------------------------------+                              
                         ¦ A new version of configuration file /etc/default/grub is available, but the version installed currently has been locally modified.  ¦                              
                         ¦                                                                                                                                     ¦                              
                         ¦ What do you want to do about modified configuration file grub?                                                                      ¦                              
                         ¦                                                                                                                                     ¦                              
                         ¦                                     install the package maintainer's version                                                        ¦                              

(Unrelated, was this too much information?)