This question already has an answer here:
After installing software with Software Updater running
sudo apt-get update
shouldn't return any hits right? This isn't the case on my system, I've installed some updates which "popped up" including security updates, but 3 days after when I run the above there are almost 30 hits (package list updates). So, this makes me wonder - does SU always run the update command before the upgrade one?