Currently Being ModeratedNov 16, 2012 1:11 PM (in response to Jack E. Tilley)
It's almost certainly a holdover from an Adobe Flash update. Normally the Adobe installer removes it shortly after installation, but even if it does, the cache doesn't always clear and so it persists for a while in Disk Utility. If the disk image itself is no longer there, you can just drag (or Command-drag) the icon out of the Disk Utility sidebar - it may remove itself if you restart your system - and you should be fine.
Currently Being ModeratedNov 16, 2012 1:31 PM (in response to Jack E. Tilley)
In addition to what vpaw just said, if you enter /var/tmp (or just look around in /var for it) in Go>Go to Folder in the Finder Menubar, you might find it's still there. As vpaw said, it's the harmless residue of the Flash Player update.