Trojan in Weather Forecast Plugin?

I just downloaded the Weather forecast plugin and Norton Internet Security removed the file, saying it was infected with a trojan named WS.Trojan.H. I'm running True Launch Bar 6.2 on a Windows 7 Home Premium machine. My virus definitions for NIS are up to date. Has anyone else encountered this? Any thoughts on whether this is a false positive?

   

This is the false positive. Not sure, but the ".part" at the end of file name means the file is not downloaded completely. Maybe this is the cause why NIS find malware there.

Anyway other antivirus software report this file is clear.

Strange - when I download the Weather Forecast plugin with Firefox, Norton throws up an alert and removes the file - just tried it again. I then tried downloading it with Chrome and NIS flagged it as clean! Weird.