@youronlyone
The recent usage is a contraction of "suspicious", with basically the same meaning. Not sure how old that is, but I don't think I'd heard it 20 years ago in the USA.
There's also "suss", which I understand is a British expression for coming to understand something or figuring something out. That usage goes back to the 1980s or earlier (I just know it from TV, it's not really US usage).