I wouldn't worry about it but for your peace of mind you can always add an extra stainless clamp yourself . But what I do is this.
I buy the black high heat resistant spray can enamel paint and I spray all over the exhaust system, and all the joints on the undercarriage . That paint really protects the surfaces from rust as well. Over the very many years of rustproofing my own vehicles this paint works the best.It is really an enamel and sticks to the surface forever and ever and probably even longer than that.