Well, a trojan is not a virus, which means that it doesn't spread by itself. And I didn't put it in there, so I'm pretty sure that it's a false positive. It's not the first time that that has happened... The fact that only 2 scanners find it would also indicate that.
But, if you don't want to install this version 4.21 (which I can imagine), you could use the work-in-progress version listed on the following thread:
viewtopic.php?f=6&t=644&start=110
I had never heard of VirusTotal, but I'll use it from now on before releasing new versions!
I expect to have a new version (4.22) ready by the end of this weekend.
Edit: AdAgent... So it's adware, not a trojan. Those also don't spread automatically.