Is there another virus checker that performs a similar check? While it's certainly within the realm of possibility that some server that tequila is connecting to could, at some point, have had malware infection, Tequila has been in use for years without any issues. Moreover; it's not a web browser and I'd be surprised if there's any opportunity for a "man in the middle" attack to even work. It doesn't send personal information. It doesn't download, install, or even support any kind of browser extensions. It just downloads client files and launches the client you choose. It doesn't actually do anything that malware of the sort your virus checker is describing could exploit.
It seems way more likely to be a false positive.