While it is possible you got a batch with corrosive primers, but your report would be a lot more credible had you cleaned your rifle and then found corrosion. Corrosive primers are not dissolved by gun cleaning oils, as oil does not dissolve salt.
However you left your rifle dirty for unspecified amount of time and found rust. The hot and humid state in which I live is a positive desert environment compared to Florida, and if I were to leave one of my rifles out, un cleaned, having been fired with non corrosive primers, I would find rust.