Warning About Free Texas Calculatem

Someone on rgp posted that Texas Calculatem is now free, so I went to the website and downloaded it, my AVG immediately flashed up that it was Trojan Horse Backdoor, I deleted it immediately. It seems to be the official site, and it indeed does say it is now free. Could my AVG be making a mistake? I was very annoyed when it came up that it was a virus

Trev