Raspbian fsck fails on boot

I used

sudo touch /forcefsck

to set my Pi to run a fsck at boot, but it failed with this message:

"An automatic check (fsck) of the root filesystem failed. A manual fsck must 
be performed, then the system restarted. The fsck should be performed in 
maintenance mode with the root filesystem mounted in read-only mode"

I ran  sudo fsck /dev/mmcblk0p2 – there was a couple of errors that required a ‘y’ to fix, and then it completed. Rebooted, and back to normal. Similar discussion on this message here.