Hi Sara,
You’re response was correct. I’ve personally never came a acrosstamp would most liks a client that ask what you’re were asked to do. Anyways, you’re out of state would not be applicable, especially a for a grading plan, unless that jurisdiction allows it. When I worked in South Florida, the city/agency would only accept plans from a Civil Engineer, some or most jurisdictions in Fl. didn’t abide to accept LA’s.to stamp grading plans. I don’t know for Site plans.
Best of luck
Jim