The legit version comes up as a trojan too Twisted. Jay did explain why this happens, but I forgot. :P
This is a common false positive as others have pointed out. Some not-so-good AV apps will flag obfuscated programs as a precaution because it is often used by skids to try and hide dangerous code. That isn't the case here (was used to prevent decompiling and cracking). Also homebrew apps that use some form of online login system also tend to produce false positives as Jay said. I had it happen twice in one of my apps.