Not likely, unless you asked them for it. If they were serving alcohol to people who didn't ask it creates a lot of issues with their liquor license. Also, frankly, alcohol isn't cheap and everywhere I've been that serves alcohol will more than anything try and get away with serving you less than what you wanted. With health & safety and food hygiene laws, glasses will have been cleaned thoroughly (most places seem to have basically a sort of big autoclave that does it), so it's unlikely to be residue.
It makes zero sense to assume a soft drink you ordered had alcohol in it...simply, you are not valuable enough as an individual to risk legal issues and losing their license to intentionally put it in, and the threat of it happening at all is not worth allowing the possibility for by cutting corners in those areas for the same reasons.