Unexpected firewall application block on ancient JPG file - malware?

Hi all,

 

Today I saw a strange application blocking alert from Norton Firewall v5.5 for Mac. It blocked an outgoing connection claiming the "Application" was an ancient JPG file from my iPhoto library which I haven't looked at in years:

 

/Users/andrew/Pictures/iPhoto Library/Previews/2009/Viewing 3, 3 Apr 2009/IMG_0096.JPG

 

It said the user was root as well, rather than the username I actually log in as.

 

This strikes me as rather suspicious. I don't see how a JPG file can be a legitimate application, particularly not when running as root.

 

What is the likelihood I have been infected with malware here? Can anyone suggest how I can investigate further?

 

Thanks very much in advance!

 

Andrew