It may or may not have been a genuine infection. Rather than have Norton delete it it may have been a good idea to submit it, either to them for further testing, and most definitely to McAfee Threat Center.
No anti-virus on the market is proof against everything out there so it's always best to have some extra anti-spyware applications installed just in case.
Send a file to Avert for analysis:
Email file to: [EMAIL="firstname.lastname@example.org"]email@example.com
When submitting samples via E-mail all samples must be packaged in a .ZIP file. When creating this .ZIP file, it is important to understand that the .ZIP can be no more than 3 megabytes in size and can contain no more than 30 files. Additionally, any .ZIP file created must be password-protected using the password "infected" (minus the ""). Failure to follow these guidelines will cause your submission to be rejected.
Also see *Unofficial* Increase In Size Of Submissions To Threat Center
We show a few free ones here: http://community.mcafee.com/showthread.php?t=136913