Download Insight

I recently downloaded the one-time pc tuneup from AVG, and I have Norton set to always display download insight notifications automatically to make sure I know what I am downloading.  However, this notification never appeared throughout the whole installation process of the tuneup program.  I checked in Norton's security history in the download insight tab, and Norton didn't know that I downloaded the program!  I scanned it and the program is safe, but I am concerned that other programs may be able to install themselves on my computer without my knowledge if download insight isn't working properly.  Is there anything I should do to make sure this doesn't happen again?