grub warning when updating

[Guy Marcenac <guy@posteurs.com>]

Hello,

I updated today my wheezy system.
In the update there were both a grub and kernel updates.
During install I got these messages

Setting up grub-pc (1.99-27+deb7u2) ...
/usr/sbin/grub-setup: warn: Attempting to install GRUB to a 
partitionless disk or to a partition.  This is a BAD idea..
/usr/sbin/grub-setup: warn: Embedding is not possible.  GRUB can only be 
installed in this setup by using blocklists.  However, blocklists are 
UNRELIABLE and their use is discouraged..
Installation finished. No error reported.
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.2.0-4-amd64
Found initrd image: /boot/initrd.img-3.2.0-4-amd64
Warning: update-grub_lib is deprecated, use grub-mkconfig_lib instead
Found linux image: /boot/bzImage-2.6.38.2-xxxx-grs-ipv6-64
done

Since this update I did not dare rebooting my system...
What happened?
Do I have to change my grub install, or is it OK to keep it like this?

--
Guy